13 Nov, 2008

1 commit

  • Maciej Rutecki reported:

    > I have this bug during suspend to disk:
    >
    > [ 188.592151] Enabling non-boot CPUs ...
    > [ 188.592151] SMP alternatives: switching to SMP code
    > [ 188.666058] BUG: using smp_processor_id() in preemptible
    > [00000000]
    > code: suspend_to_disk/2934
    > [ 188.666064] caller is native_sched_clock+0x2b/0x80

    Which, as noted by Linus, was caused by me, via:

    7cbaef9c "sched: optimize sched_clock() a bit"

    Move the rq locking a bit earlier in the initialization sequence,
    that will make the sched_clock() call in init_idle() non-preemptible.

    Reported-by: Maciej Rutecki
    Signed-off-by: Ingo Molnar

    Ingo Molnar
     

12 Nov, 2008

1 commit

  • Impact: fix load balancer load average calculation accuracy

    cpu_avg_load_per_task() returns a stale value when nr_running is 0.
    It returns an older stale (caculated when nr_running was non zero) value.

    This patch returns and sets rq->avg_load_per_task to zero when nr_running
    is 0.

    Compile and boot tested on a x86_64 box.

    Signed-off-by: Balbir Singh
    Acked-by: Peter Zijlstra
    Signed-off-by: Ingo Molnar

    Balbir Singh
     

11 Nov, 2008

1 commit

  • Impact: fix hang/crash on ia64 under high load

    This is ugly, but the simplest patch by far.

    Unlike other similar routines, account_group_exec_runtime() could be
    called "implicitly" from within scheduler after exit_notify(). This
    means we can race with the parent doing release_task(), we can't just
    check ->signal != NULL.

    Change __exit_signal() to do spin_unlock_wait(&task_rq(tsk)->lock)
    before __cleanup_signal() to make sure ->signal can't be freed under
    task_rq(tsk)->lock. Note that task_rq_unlock_wait() doesn't care
    about the case when tsk changes cpu/rq under us, this should be OK.

    Thanks to Ingo who nacked my previous buggy patch.

    Signed-off-by: Oleg Nesterov
    Acked-by: Peter Zijlstra
    Signed-off-by: Ingo Molnar
    Reported-by: Doug Chapman

    Oleg Nesterov
     

10 Nov, 2008

1 commit

  • Impact: clean up and fix debug info printout

    While looking over the sched_debug code I noticed that we printed the rq
    schedstats for every cfs_rq, ammend this.

    Also change nr_spead_over into an int, and fix a little buglet in
    min_vruntime printing.

    Signed-off-by: Peter Zijlstra
    Signed-off-by: Ingo Molnar

    Peter Zijlstra
     

07 Nov, 2008

2 commits

  • Impact: fix rare memory leak in the sched-domains manual reconfiguration code

    In the failure path, rd is not attached to a sched domain,
    so it causes a leak.

    Signed-off-by: Li Zefan
    Acked-by: Peter Zijlstra
    Signed-off-by: Ingo Molnar

    Li Zefan
     
  • Impact: re-add incorrectly eliminated sched domain layers

    (1) on i386 with SCHED_SMT and SCHED_MC enabled
    # mount -t cgroup -o cpuset xxx /mnt
    # echo 0 > /mnt/cpuset.sched_load_balance
    # mkdir /mnt/0
    # echo 0 > /mnt/0/cpuset.cpus
    # dmesg
    CPU0 attaching sched-domain:
    domain 0: span 0 level CPU
    groups: 0

    (2) on i386 with SCHED_MC enabled but SCHED_SMT disabled
    # same with (1)
    # dmesg
    CPU0 attaching NULL sched-domain.

    The bug is that some sched domains may be skipped unintentionally when
    degenerating (optimizing) sched domains.

    Signed-off-by: Li Zefan
    Acked-by: Peter Zijlstra
    Signed-off-by: Ingo Molnar

    Li Zefan
     

05 Nov, 2008

1 commit

  • Impact: improve/change/fix wakeup-buddy scheduling

    Currently we only have a forward looking buddy, that is, we prefer to
    schedule to the task we last woke up, under the presumption that its
    going to consume the data we just produced, and therefore will have
    cache hot benefits.

    This allows co-waking producer/consumer task pairs to run ahead of the
    pack for a little while, keeping their cache warm. Without this, we
    would interleave all pairs, utterly trashing the cache.

    This patch introduces a backward looking buddy, that is, suppose that
    in the above scenario, the consumer preempts the producer before it
    can go to sleep, we will therefore miss the wakeup from consumer to
    producer (its already running, after all), breaking the cycle and
    reverting to the cache-trashing interleaved schedule pattern.

    The backward buddy will try to schedule back to the task that woke us
    up in case the forward buddy is not available, under the assumption
    that the last task will be the one with the most cache hot task around
    barring current.

    This will basically allow a task to continue after it got preempted.

    In order to avoid starvation, we allow either buddy to get wakeup_gran
    ahead of the pack.

    Signed-off-by: Peter Zijlstra
    Acked-by: Mike Galbraith
    Signed-off-by: Ingo Molnar

    Peter Zijlstra
     

24 Oct, 2008

5 commits

  • Since we moved wakeup preemption back to virtual time, it makes sense to move
    the buddy stuff back as well. The purpose of the buddy scheduling is to allow
    a quickly scheduling pair of tasks to run away from the group as far as a
    regular busy task would be allowed under wakeup preemption.

    This has the advantage that the pair can ping-pong for a while, enjoying
    cache-hotness. Without buddy scheduling other tasks would interleave destroying
    the cache.

    Also, it saves a word in cfs_rq.

    Signed-off-by: Peter Zijlstra
    Acked-by: Mike Galbraith
    Signed-off-by: Ingo Molnar

    Peter Zijlstra
     
  • In one of the group load balancer patches:

    commit 408ed066b11cf9ee4536573b4269ee3613bd735e
    Author: Peter Zijlstra
    Date: Fri Jun 27 13:41:28 2008 +0200
    Subject: sched: hierarchical load vs find_busiest_group

    The following change:

    - if (max_load - this_load + SCHED_LOAD_SCALE_FUZZ >=
    + if (max_load - this_load + 2*busiest_load_per_task >=
    busiest_load_per_task * imbn) {

    made the condition always true, because imbn is [1,2].
    Therefore, remove the 2*, and give the it a fair chance.

    Signed-off-by: Peter Zijlstra
    Acked-by: Mike Galbraith
    Signed-off-by: Ingo Molnar

    Peter Zijlstra
     
  • * 'proc' of git://git.kernel.org/pub/scm/linux/kernel/git/adobriyan/proc: (35 commits)
    proc: remove fs/proc/proc_misc.c
    proc: move /proc/vmcore creation to fs/proc/vmcore.c
    proc: move pagecount stuff to fs/proc/page.c
    proc: move all /proc/kcore stuff to fs/proc/kcore.c
    proc: move /proc/schedstat boilerplate to kernel/sched_stats.h
    proc: move /proc/modules boilerplate to kernel/module.c
    proc: move /proc/diskstats boilerplate to block/genhd.c
    proc: move /proc/zoneinfo boilerplate to mm/vmstat.c
    proc: move /proc/vmstat boilerplate to mm/vmstat.c
    proc: move /proc/pagetypeinfo boilerplate to mm/vmstat.c
    proc: move /proc/buddyinfo boilerplate to mm/vmstat.c
    proc: move /proc/vmallocinfo to mm/vmalloc.c
    proc: move /proc/slabinfo boilerplate to mm/slub.c, mm/slab.c
    proc: move /proc/slab_allocators boilerplate to mm/slab.c
    proc: move /proc/interrupts boilerplate code to fs/proc/interrupts.c
    proc: move /proc/stat to fs/proc/stat.c
    proc: move rest of /proc/partitions code to block/genhd.c
    proc: move /proc/cpuinfo code to fs/proc/cpuinfo.c
    proc: move /proc/devices code to fs/proc/devices.c
    proc: move rest of /proc/locks to fs/locks.c
    ...

    Linus Torvalds
     
  • …inux/kernel/git/tip/linux-2.6-tip

    * 'v28-range-hrtimers-for-linus-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (37 commits)
    hrtimers: add missing docbook comments to struct hrtimer
    hrtimers: simplify hrtimer_peek_ahead_timers()
    hrtimers: fix docbook comments
    DECLARE_PER_CPU needs linux/percpu.h
    hrtimers: fix typo
    rangetimers: fix the bug reported by Ingo for real
    rangetimer: fix BUG_ON reported by Ingo
    rangetimer: fix x86 build failure for the !HRTIMERS case
    select: fix alpha OSF wrapper
    select: fix alpha OSF wrapper
    hrtimer: peek at the timer queue just before going idle
    hrtimer: make the futex() system call use the per process slack value
    hrtimer: make the nanosleep() syscall use the per process slack
    hrtimer: fix signed/unsigned bug in slack estimator
    hrtimer: show the timer ranges in /proc/timer_list
    hrtimer: incorporate feedback from Peter Zijlstra
    hrtimer: add a hrtimer_start_range() function
    hrtimer: another build fix
    hrtimer: fix build bug found by Ingo
    hrtimer: make select() and poll() use the hrtimer range feature
    ...

    Linus Torvalds
     
  • …l/git/tip/linux-2.6-tip

    * 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
    sched: disable the hrtick for now
    sched: revert back to per-rq vruntime
    sched: fair scheduler should not resched rt tasks
    sched: optimize group load balancer
    sched: minor fast-path overhead reduction
    sched: fix the wrong mask_len, cleanup
    sched: kill unused scheduler decl.
    sched: fix the wrong mask_len
    sched: only update rq->clock while holding rq->lock

    Linus Torvalds
     

23 Oct, 2008

1 commit


22 Oct, 2008

1 commit


21 Oct, 2008

1 commit

  • …l/git/tip/linux-2.6-tip

    * 'tracing-v28-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (131 commits)
    tracing/fastboot: improve help text
    tracing/stacktrace: improve help text
    tracing/fastboot: fix initcalls disposition in bootgraph.pl
    tracing/fastboot: fix bootgraph.pl initcall name regexp
    tracing/fastboot: fix issues and improve output of bootgraph.pl
    tracepoints: synchronize unregister static inline
    tracepoints: tracepoint_synchronize_unregister()
    ftrace: make ftrace_test_p6nop disassembler-friendly
    markers: fix synchronize marker unregister static inline
    tracing/fastboot: add better resolution to initcall debug/tracing
    trace: add build-time check to avoid overrunning hex buffer
    ftrace: fix hex output mode of ftrace
    tracing/fastboot: fix initcalls disposition in bootgraph.pl
    tracing/fastboot: fix printk format typo in boot tracer
    ftrace: return an error when setting a nonexistent tracer
    ftrace: make some tracers reentrant
    ring-buffer: make reentrant
    ring-buffer: move page indexes into page headers
    tracing/fastboot: only trace non-module initcalls
    ftrace: move pc counter in irqtrace
    ...

    Manually fix conflicts:
    - init/main.c: initcall tracing
    - kernel/module.c: verbose level vs tracepoints
    - scripts/bootgraph.pl: fallout from cherry-picking commits.

    Linus Torvalds
     

20 Oct, 2008

2 commits


18 Oct, 2008

1 commit


16 Oct, 2008

1 commit

  • Vatsa noticed rq->clock going funny and tracked it down to an update_rq_clock()
    outside a rq->lock section.

    This is a problem because things like double_rq_lock() update the rq->clock
    value for both rqs. Therefore disabling interrupts isn't strong enough.

    Reported-by: Srivatsa Vaddagiri
    Signed-off-by: Peter Zijlstra
    Signed-off-by: Ingo Molnar

    Peter Zijlstra
     

14 Oct, 2008

1 commit

  • Instrument the scheduler activity (sched_switch, migration, wakeups,
    wait for a task, signal delivery) and process/thread
    creation/destruction (fork, exit, kthread stop). Actually, kthread
    creation is not instrumented in this patch because it is architecture
    dependent. It allows to connect tracers such as ftrace which detects
    scheduling latencies, good/bad scheduler decisions. Tools like LTTng can
    export this scheduler information along with instrumentation of the rest
    of the kernel activity to perform post-mortem analysis on the scheduler
    activity.

    About the performance impact of tracepoints (which is comparable to
    markers), even without immediate values optimizations, tests done by
    Hideo Aoki on ia64 show no regression. His test case was using hackbench
    on a kernel where scheduler instrumentation (about 5 events in code
    scheduler code) was added. See the "Tracepoints" patch header for
    performance result detail.

    Changelog :

    - Change instrumentation location and parameter to match ftrace
    instrumentation, previously done with kernel markers.

    [ mingo@elte.hu: conflict resolutions ]
    Signed-off-by: Mathieu Desnoyers
    Acked-by: 'Peter Zijlstra'
    Signed-off-by: Ingo Molnar

    Mathieu Desnoyers
     

09 Oct, 2008

1 commit

  • add /proc/sys/kernel/sched_domain/cpu0/domain0/name, to make
    it easier to see which specific scheduler domain remained at
    that entry.

    Since we process the scheduler domain tree and
    simplify it, it's not always immediately clear during debugging
    which domain came from where.

    depends on CONFIG_SCHED_DEBUG=y.

    Signed-off-by: Ingo Molnar

    Ingo Molnar
     

06 Oct, 2008

2 commits


30 Sep, 2008

1 commit


29 Sep, 2008

1 commit

  • Impact: per CPU hrtimers can be migrated from a dead CPU

    The hrtimer code has no knowledge about per CPU timers, but we need to
    prevent the migration of such timers and warn when such a timer is
    active at migration time.

    Explicitely mark the timers as per CPU and use a more understandable
    mode descriptor for the interrupts safe unlocked callback mode, which
    is used by hrtimer_sleeper and the scheduler code.

    Signed-off-by: Thomas Gleixner

    Thomas Gleixner
     

28 Sep, 2008

1 commit


23 Sep, 2008

5 commits

  • While playing around with it, I noticed we missed some sanity checks.
    Also add some comments while we're there.

    Signed-off-by: Peter Zijlstra
    Signed-off-by: Ingo Molnar

    Peter Zijlstra
     
  • Ingo Molnar
     
  • This is the second resubmission of the posix timer rework patch, posted
    a few days ago.

    This includes the changes from the previous resubmittion, which addressed
    Oleg Nesterov's comments, removing the RCU stuff from the patch and
    un-inlining the thread_group_cputime() function for SMP.

    In addition, per Ingo Molnar it simplifies the UP code, consolidating much
    of it with the SMP version and depending on lower-level SMP/UP handling to
    take care of the differences.

    It also cleans up some UP compile errors, moves the scheduler stats-related
    macros into kernel/sched_stats.h, cleans up a merge error in
    kernel/fork.c and has a few other minor fixes and cleanups as suggested
    by Oleg and Ingo. Thanks for the review, guys.

    Signed-off-by: Frank Mayhar
    Cc: Roland McGrath
    Cc: Alexey Dobriyan
    Cc: Andrew Morton
    Signed-off-by: Ingo Molnar

    Frank Mayhar
     
  • - Add some comments to try to make the ifdef puzzle a bit clearer

    - Explicitly inline one of the three init_hrtick() implementations.

    Signed-off-by: Andrew Morton
    Signed-off-by: Ingo Molnar

    Andrew Morton
     
  • LD kernel/built-in.o
    WARNING: kernel/built-in.o(.text+0x326): Section mismatch in reference
    from the function init_hrtick() to the variable
    .cpuinit.data:hotplug_hrtick_nb.8
    The function init_hrtick() references
    the variable __cpuinitdata hotplug_hrtick_nb.8.
    This is often because init_hrtick lacks a __cpuinitdata
    annotation or the annotation of hotplug_hrtick_nb.8 is wrong.

    Signed-off-by: Md.Rakib H. Mullick
    Signed-off-by: Andrew Morton
    Signed-off-by: Ingo Molnar

    Rakib Mullick
     

22 Sep, 2008

1 commit

  • Lin Ming reported a 10% OLTP regression against 2.6.27-rc4.

    The difference seems to come from different preemption agressiveness,
    which affects the cache footprint of the workload and its effective
    cache trashing.

    Aggresively preempt a task if its avg overlap is very small, this should
    avoid the task going to sleep and find it still running when we schedule
    back to it - saving a wakeup.

    Reported-by: Lin Ming
    Signed-off-by: Peter Zijlstra
    Signed-off-by: Ingo Molnar

    Peter Zijlstra
     

14 Sep, 2008

1 commit

  • Overview

    This patch reworks the handling of POSIX CPU timers, including the
    ITIMER_PROF, ITIMER_VIRT timers and rlimit handling. It was put together
    with the help of Roland McGrath, the owner and original writer of this code.

    The problem we ran into, and the reason for this rework, has to do with using
    a profiling timer in a process with a large number of threads. It appears
    that the performance of the old implementation of run_posix_cpu_timers() was
    at least O(n*3) (where "n" is the number of threads in a process) or worse.
    Everything is fine with an increasing number of threads until the time taken
    for that routine to run becomes the same as or greater than the tick time, at
    which point things degrade rather quickly.

    This patch fixes bug 9906, "Weird hang with NPTL and SIGPROF."

    Code Changes

    This rework corrects the implementation of run_posix_cpu_timers() to make it
    run in constant time for a particular machine. (Performance may vary between
    one machine and another depending upon whether the kernel is built as single-
    or multiprocessor and, in the latter case, depending upon the number of
    running processors.) To do this, at each tick we now update fields in
    signal_struct as well as task_struct. The run_posix_cpu_timers() function
    uses those fields to make its decisions.

    We define a new structure, "task_cputime," to contain user, system and
    scheduler times and use these in appropriate places:

    struct task_cputime {
    cputime_t utime;
    cputime_t stime;
    unsigned long long sum_exec_runtime;
    };

    This is included in the structure "thread_group_cputime," which is a new
    substructure of signal_struct and which varies for uniprocessor versus
    multiprocessor kernels. For uniprocessor kernels, it uses "task_cputime" as
    a simple substructure, while for multiprocessor kernels it is a pointer:

    struct thread_group_cputime {
    struct task_cputime totals;
    };

    struct thread_group_cputime {
    struct task_cputime *totals;
    };

    We also add a new task_cputime substructure directly to signal_struct, to
    cache the earliest expiration of process-wide timers, and task_cputime also
    replaces the it_*_expires fields of task_struct (used for earliest expiration
    of thread timers). The "thread_group_cputime" structure contains process-wide
    timers that are updated via account_user_time() and friends. In the non-SMP
    case the structure is a simple aggregator; unfortunately in the SMP case that
    simplicity was not achievable due to cache-line contention between CPUs (in
    one measured case performance was actually _worse_ on a 16-cpu system than
    the same test on a 4-cpu system, due to this contention). For SMP, the
    thread_group_cputime counters are maintained as a per-cpu structure allocated
    using alloc_percpu(). The timer functions update only the timer field in
    the structure corresponding to the running CPU, obtained using per_cpu_ptr().

    We define a set of inline functions in sched.h that we use to maintain the
    thread_group_cputime structure and hide the differences between UP and SMP
    implementations from the rest of the kernel. The thread_group_cputime_init()
    function initializes the thread_group_cputime structure for the given task.
    The thread_group_cputime_alloc() is a no-op for UP; for SMP it calls the
    out-of-line function thread_group_cputime_alloc_smp() to allocate and fill
    in the per-cpu structures and fields. The thread_group_cputime_free()
    function, also a no-op for UP, in SMP frees the per-cpu structures. The
    thread_group_cputime_clone_thread() function (also a UP no-op) for SMP calls
    thread_group_cputime_alloc() if the per-cpu structures haven't yet been
    allocated. The thread_group_cputime() function fills the task_cputime
    structure it is passed with the contents of the thread_group_cputime fields;
    in UP it's that simple but in SMP it must also safely check that tsk->signal
    is non-NULL (if it is it just uses the appropriate fields of task_struct) and,
    if so, sums the per-cpu values for each online CPU. Finally, the three
    functions account_group_user_time(), account_group_system_time() and
    account_group_exec_runtime() are used by timer functions to update the
    respective fields of the thread_group_cputime structure.

    Non-SMP operation is trivial and will not be mentioned further.

    The per-cpu structure is always allocated when a task creates its first new
    thread, via a call to thread_group_cputime_clone_thread() from copy_signal().
    It is freed at process exit via a call to thread_group_cputime_free() from
    cleanup_signal().

    All functions that formerly summed utime/stime/sum_sched_runtime values from
    from all threads in the thread group now use thread_group_cputime() to
    snapshot the values in the thread_group_cputime structure or the values in
    the task structure itself if the per-cpu structure hasn't been allocated.

    Finally, the code in kernel/posix-cpu-timers.c has changed quite a bit.
    The run_posix_cpu_timers() function has been split into a fast path and a
    slow path; the former safely checks whether there are any expired thread
    timers and, if not, just returns, while the slow path does the heavy lifting.
    With the dedicated thread group fields, timers are no longer "rebalanced" and
    the process_timer_rebalance() function and related code has gone away. All
    summing loops are gone and all code that used them now uses the
    thread_group_cputime() inline. When process-wide timers are set, the new
    task_cputime structure in signal_struct is used to cache the earliest
    expiration; this is checked in the fast path.

    Performance

    The fix appears not to add significant overhead to existing operations. It
    generally performs the same as the current code except in two cases, one in
    which it performs slightly worse (Case 5 below) and one in which it performs
    very significantly better (Case 2 below). Overall it's a wash except in those
    two cases.

    I've since done somewhat more involved testing on a dual-core Opteron system.

    Case 1: With no itimer running, for a test with 100,000 threads, the fixed
    kernel took 1428.5 seconds, 513 seconds more than the unfixed system,
    all of which was spent in the system. There were twice as many
    voluntary context switches with the fix as without it.

    Case 2: With an itimer running at .01 second ticks and 4000 threads (the most
    an unmodified kernel can handle), the fixed kernel ran the test in
    eight percent of the time (5.8 seconds as opposed to 70 seconds) and
    had better tick accuracy (.012 seconds per tick as opposed to .023
    seconds per tick).

    Case 3: A 4000-thread test with an initial timer tick of .01 second and an
    interval of 10,000 seconds (i.e. a timer that ticks only once) had
    very nearly the same performance in both cases: 6.3 seconds elapsed
    for the fixed kernel versus 5.5 seconds for the unfixed kernel.

    With fewer threads (eight in these tests), the Case 1 test ran in essentially
    the same time on both the modified and unmodified kernels (5.2 seconds versus
    5.8 seconds). The Case 2 test ran in about the same time as well, 5.9 seconds
    versus 5.4 seconds but again with much better tick accuracy, .013 seconds per
    tick versus .025 seconds per tick for the unmodified kernel.

    Since the fix affected the rlimit code, I also tested soft and hard CPU limits.

    Case 4: With a hard CPU limit of 20 seconds and eight threads (and an itimer
    running), the modified kernel was very slightly favored in that while
    it killed the process in 19.997 seconds of CPU time (5.002 seconds of
    wall time), only .003 seconds of that was system time, the rest was
    user time. The unmodified kernel killed the process in 20.001 seconds
    of CPU (5.014 seconds of wall time) of which .016 seconds was system
    time. Really, though, the results were too close to call. The results
    were essentially the same with no itimer running.

    Case 5: With a soft limit of 20 seconds and a hard limit of 2000 seconds
    (where the hard limit would never be reached) and an itimer running,
    the modified kernel exhibited worse tick accuracy than the unmodified
    kernel: .050 seconds/tick versus .028 seconds/tick. Otherwise,
    performance was almost indistinguishable. With no itimer running this
    test exhibited virtually identical behavior and times in both cases.

    In times past I did some limited performance testing. those results are below.

    On a four-cpu Opteron system without this fix, a sixteen-thread test executed
    in 3569.991 seconds, of which user was 3568.435s and system was 1.556s. On
    the same system with the fix, user and elapsed time were about the same, but
    system time dropped to 0.007 seconds. Performance with eight, four and one
    thread were comparable. Interestingly, the timer ticks with the fix seemed
    more accurate: The sixteen-thread test with the fix received 149543 ticks
    for 0.024 seconds per tick, while the same test without the fix received 58720
    for 0.061 seconds per tick. Both cases were configured for an interval of
    0.01 seconds. Again, the other tests were comparable. Each thread in this
    test computed the primes up to 25,000,000.

    I also did a test with a large number of threads, 100,000 threads, which is
    impossible without the fix. In this case each thread computed the primes only
    up to 10,000 (to make the runtime manageable). System time dominated, at
    1546.968 seconds out of a total 2176.906 seconds (giving a user time of
    629.938s). It received 147651 ticks for 0.015 seconds per tick, still quite
    accurate. There is obviously no comparable test without the fix.

    Signed-off-by: Frank Mayhar
    Cc: Roland McGrath
    Cc: Alexey Dobriyan
    Cc: Andrew Morton
    Signed-off-by: Ingo Molnar

    Frank Mayhar
     

11 Sep, 2008

2 commits

  • Ingo Molnar
     
  • Andrei Gusev wrote:

    > I played witch scheduler settings. After doing something like:
    > echo -n 1000000 >sched_rt_period_us
    >
    > command is locked. I found in kernel.log:
    >
    > Sep 11 00:39:34 zaratustra
    > Sep 11 00:39:34 zaratustra Pid: 4495, comm: bash Tainted: G W
    > (2.6.26.3 #12)
    > Sep 11 00:39:34 zaratustra EIP: 0060:[] EFLAGS: 00210246 CPU: 0
    > Sep 11 00:39:34 zaratustra EIP is at div64_u64+0x57/0x80
    > Sep 11 00:39:34 zaratustra EAX: 0000389f EBX: 00000000 ECX: 00000000
    > EDX: 00000000
    > Sep 11 00:39:34 zaratustra ESI: d9800000 EDI: d9800000 EBP: 0000389f
    > ESP: ea7a6edc
    > Sep 11 00:39:34 zaratustra DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 0068
    > Sep 11 00:39:34 zaratustra Process bash (pid: 4495, ti=ea7a6000
    > task=ea744000 task.ti=ea7a6000)
    > Sep 11 00:39:34 zaratustra Stack: 00000000 000003e8 d9800000 0000389f
    > c0119042 00000000 00000000 00000001
    > Sep 11 00:39:34 zaratustra 00000000 00000000 ea7a6f54 00010000 00000000
    > c04d2e80 00000001 000e7ef0
    > Sep 11 00:39:34 zaratustra c01191a3 00000000 00000000 ea7a6fa0 00000001
    > ffffffff c04d2e80 ea5b2480
    > Sep 11 00:39:34 zaratustra Call Trace:
    > Sep 11 00:39:34 zaratustra [] __rt_schedulable+0x52/0x130
    > Sep 11 00:39:34 zaratustra [] sched_rt_handler+0x83/0x120
    > Sep 11 00:39:34 zaratustra [] proc_sys_call_handler+0xb6/0xd0
    > Sep 11 00:39:34 zaratustra [] proc_sys_write+0x0/0x20
    > Sep 11 00:39:34 zaratustra [] proc_sys_write+0x19/0x20
    > Sep 11 00:39:34 zaratustra [] vfs_write+0xa8/0x140
    > Sep 11 00:39:34 zaratustra [] sys_write+0x41/0x80
    > Sep 11 00:39:34 zaratustra [] sysenter_past_esp+0x6a/0x91
    > Sep 11 00:39:34 zaratustra =======================
    > Sep 11 00:39:34 zaratustra Code: c8 41 0f ad f3 d3 ee f6 c1 20 0f 45 de
    > 31 f6 0f ad ef d3 ed f6 c1 20 0f 45 fd 0f 45 ee 31 c9 39 eb 89 fe 89 ea
    > 77 08 89 e8 31 d2 f3 89 c1 89 f0 8b 7c 24 08 f7 f3 8b 74 24 04 89
    > ca 8b 1c 24
    > Sep 11 00:39:34 zaratustra EIP: [] div64_u64+0x57/0x80 SS:ESP
    > 0068:ea7a6edc
    > Sep 11 00:39:34 zaratustra ---[ end trace 4eaa2a86a8e2da22 ]---

    fix the boundary condition.

    sysctl_sched_rt_period=0 makes exception at to_ratio().

    Signed-off-by: Hiroshi Shimamoto
    Signed-off-by: Ingo Molnar

    Hiroshi Shimamoto
     

07 Sep, 2008

2 commits

  • Ingo Molnar
     
  • What I realized recently is that calling rebuild_sched_domains() in
    arch_reinit_sched_domains() by itself is not enough when cpusets are enabled.
    partition_sched_domains() code is trying to avoid unnecessary domain rebuilds
    and will not actually rebuild anything if new domain masks match the old ones.

    What this means is that doing
    echo 1 > /sys/devices/system/cpu/sched_mc_power_savings
    on a system with cpusets enabled will not take affect untill something changes
    in the cpuset setup (ie new sets created or deleted).

    This patch fixes restore correct behaviour where domains must be rebuilt in
    order to enable MC powersaving flags.

    Test on quad-core Core2 box with both CONFIG_CPUSETS and !CONFIG_CPUSETS.
    Also tested on dual-core Core2 laptop. Lockdep is happy and things are working
    as expected.

    Signed-off-by: Max Krasnyansky
    Tested-by: Vaidyanathan Srinivasan
    Signed-off-by: Ingo Molnar

    Max Krasnyansky
     

06 Sep, 2008

3 commits

  • Ingo Molnar
     
  • I found that 2.6.27-rc5-mm1 does not compile with gcc 3.4.6.
    The error is:
    CC kernel/sched.o
    kernel/sched.c: In function `start_rt_bandwidth':
    kernel/sched.c:208: sorry, unimplemented: inlining failed in call to 'rt_bandwidth_enabled': function body not available
    kernel/sched.c:214: sorry, unimplemented: called from here
    make[1]: *** [kernel/sched.o] Error 1
    make: *** [kernel] Error 2

    It seems that the gcc 3.4.6 requires full inline definition before first usage.
    The patch below fixes the compilation problem.

    Signed-off-by: Krzysztof Helt (if needed>
    Signed-off-by: Ingo Molnar

    Krzysztof Helt
     
  • In order to be able to do range hrtimers we need to use accessor functions
    to the "expire" member of the hrtimer struct.
    This patch converts kernel/* to these accessors.

    Signed-off-by: Arjan van de Ven

    Arjan van de Ven