Eric Lee / linux-smarc-t335x-v3.2

01 Mar, 2010

15 commits

27 Dec, 2009

2 commits

23 Dec, 2009

1 commit

  • 628ff7c1d   anonfd: Allow making anon files read-only ... Browse Code »

    It seems a couple places such as arch/ia64/kernel/perfmon.c and
    drivers/infiniband/core/uverbs_main.c could use anon_inode_getfile()
    instead of a private pseudo-fs + alloc_file(), if only there were a way
    to get a read-only file. So provide this by having anon_inode_getfile()
    create a read-only file if we pass O_RDONLY in flags.

    Signed-off-by: Roland Dreier
    Signed-off-by: Al Viro

    Roland Dreier
     

09 Dec, 2009

1 commit

03 Dec, 2009

9 commits

05 Nov, 2009

1 commit

  • c8240bd6f   Use Little Endian for Dirty Bitmap ... Browse Code »

    We currently use host endian long types to store information
    in the dirty bitmap.

    This works reasonably well on Little Endian targets, because the
    u32 after the first contains the next 32 bits. On Big Endian this
    breaks completely though, forcing us to be inventive here.

    So Ben suggested to always use Little Endian, which looks reasonable.

    We only have dirty bitmap implemented in Little Endian targets so far
    and since PowerPC would be the first Big Endian platform, we can just
    as well switch to Little Endian always with little effort without
    breaking existing targets.

    Signed-off-by: Alexander Graf
    Signed-off-by: Benjamin Herrenschmidt

    Alexander Graf
     

16 Oct, 2009

1 commit

04 Oct, 2009

1 commit

02 Oct, 2009

1 commit

28 Sep, 2009

1 commit

24 Sep, 2009

1 commit

10 Sep, 2009

6 commits

  • 28bcb1121   KVM: fix compile warnings on s390 ... Browse Code »

    CC arch/s390/kvm/../../../virt/kvm/kvm_main.o
    arch/s390/kvm/../../../virt/kvm/kvm_main.c: In function '__kvm_set_memory_region':
    arch/s390/kvm/../../../virt/kvm/kvm_main.c:485: warning: unused variable 'j'
    arch/s390/kvm/../../../virt/kvm/kvm_main.c:484: warning: unused variable 'lpages'
    arch/s390/kvm/../../../virt/kvm/kvm_main.c:483: warning: unused variable 'ugfn'

    Cc: Carsten Otte
    Signed-off-by: Heiko Carstens
    Signed-off-by: Marcelo Tosatti

    Heiko Carstens
     
  • 6621fbc2c   KVM: Move #endif KVM_CAP_IRQ_ROUTING to correct place ... Browse Code »

    The symbol only controls irq routing, not MSI-X.

    Signed-off-by: Avi Kivity

    Avi Kivity
     
  • aed665f7b   KVM: fix kvm_init() error handling ... Browse Code »

    Remove debugfs file if kvm_arch_init() return error

    Signed-off-by: Xiao Guangrong
    Signed-off-by: Avi Kivity

    Xiao Guangrong
     
  • e601e3be7   KVM: Drop obsolete cpu_get/put in make_all_cpus_request ... Browse Code »

    spin_lock disables preemption, so we can simply read the current cpu.

    Signed-off-by: Jan Kiszka
    Signed-off-by: Marcelo Tosatti

    Jan Kiszka
     
  • a1b37100d   KVM: Reduce runnability interface with arch support code ... Browse Code »

    Remove kvm_cpu_has_interrupt() and kvm_arch_interrupt_allowed() from
    interface between general code and arch code. kvm_arch_vcpu_runnable()
    checks for interrupts instead.

    Signed-off-by: Gleb Natapov
    Signed-off-by: Avi Kivity

    Gleb Natapov
     
  • d34e6b175   KVM: add ioeventfd support ... Browse Code »

    ioeventfd is a mechanism to register PIO/MMIO regions to trigger an eventfd
    signal when written to by a guest. Host userspace can register any
    arbitrary IO address with a corresponding eventfd and then pass the eventfd
    to a specific end-point of interest for handling.

    Normal IO requires a blocking round-trip since the operation may cause
    side-effects in the emulated model or may return data to the caller.
    Therefore, an IO in KVM traps from the guest to the host, causes a VMX/SVM
    "heavy-weight" exit back to userspace, and is ultimately serviced by qemu's
    device model synchronously before returning control back to the vcpu.

    However, there is a subclass of IO which acts purely as a trigger for
    other IO (such as to kick off an out-of-band DMA request, etc). For these
    patterns, the synchronous call is particularly expensive since we really
    only want to simply get our notification transmitted asychronously and
    return as quickly as possible. All the sychronous infrastructure to ensure
    proper data-dependencies are met in the normal IO case are just unecessary
    overhead for signalling. This adds additional computational load on the
    system, as well as latency to the signalling path.

    Therefore, we provide a mechanism for registration of an in-kernel trigger
    point that allows the VCPU to only require a very brief, lightweight
    exit just long enough to signal an eventfd. This also means that any
    clients compatible with the eventfd interface (which includes userspace
    and kernelspace equally well) can now register to be notified. The end
    result should be a more flexible and higher performance notification API
    for the backend KVM hypervisor and perhipheral components.

    To test this theory, we built a test-harness called "doorbell". This
    module has a function called "doorbell_ring()" which simply increments a
    counter for each time the doorbell is signaled. It supports signalling
    from either an eventfd, or an ioctl().

    We then wired up two paths to the doorbell: One via QEMU via a registered
    io region and through the doorbell ioctl(). The other is direct via
    ioeventfd.

    You can download this test harness here:

    ftp://ftp.novell.com/dev/ghaskins/doorbell.tar.bz2

    The measured results are as follows:

    qemu-mmio: 110000 iops, 9.09us rtt
    ioeventfd-mmio: 200100 iops, 5.00us rtt
    ioeventfd-pio: 367300 iops, 2.72us rtt

    I didn't measure qemu-pio, because I have to figure out how to register a
    PIO region with qemu's device model, and I got lazy. However, for now we
    can extrapolate based on the data from the NULLIO runs of +2.56us for MMIO,
    and -350ns for HC, we get:

    qemu-pio: 153139 iops, 6.53us rtt
    ioeventfd-hc: 412585 iops, 2.37us rtt

    these are just for fun, for now, until I can gather more data.

    Here is a graph for your convenience:

    http://developer.novell.com/wiki/images/7/76/Iofd-chart.png

    The conclusion to draw is that we save about 4us by skipping the userspace
    hop.

    --------------------

    Signed-off-by: Gregory Haskins
    Acked-by: Michael S. Tsirkin
    Signed-off-by: Avi Kivity

    Gregory Haskins