Eric Lee / smarc-ti-linux-kernel

13 Mar, 2014

1 commit

  • 89f8b33ca   block: remove old blk_iopoll_enabled variable ... Browse Code »

    This was a debugging measure to toggle enabled/disabled
    when testing. But for real production setups, it's not
    safe to toggle this setting without either reloading
    drivers of quiescing IO first. Neither of which the toggle
    enforces.

    Additionally, it makes drivers deal with the conditional
    state.

    Remove it completely. It's up to the driver whether iopoll
    is enabled or not.

    Signed-off-by: Jens Axboe

    Jens Axboe
     

08 Nov, 2013

1 commit

  • 170d800af   block: Replace __get_cpu_var uses ... Browse Code »

    __get_cpu_var() is used for multiple purposes in the kernel source. One of
    them is address calculation via the form &__get_cpu_var(x). This calculates
    the address for the instance of the percpu variable of the current processor
    based on an offset.

    Other use cases are for storing and retrieving data from the current
    processors percpu area. __get_cpu_var() can be used as an lvalue when
    writing data or on the right side of an assignment.

    __get_cpu_var() is defined as :

    #define __get_cpu_var(var) (*this_cpu_ptr(&(var)))

    __get_cpu_var() always only does an address determination. However, store
    and retrieve operations could use a segment prefix (or global register on
    other platforms) to avoid the address calculation.

    this_cpu_write() and this_cpu_read() can directly take an offset into a
    percpu area and use optimized assembly code to read and write per cpu
    variables.

    This patch converts __get_cpu_var into either an explicit address
    calculation using this_cpu_ptr() or into a use of this_cpu operations that
    use the offset. Thereby address calculations are avoided and less registers
    are used when code is generated.

    At the end of the patch set all uses of __get_cpu_var have been removed so
    the macro is removed too.

    The patch set includes passes over all arches as well. Once these operations
    are used throughout then specialized macros can be defined in non -x86
    arches as well in order to optimize per cpu access by f.e. using a global
    register that may be set to the per cpu base.

    Transformations done to __get_cpu_var()

    1. Determine the address of the percpu instance of the current processor.

    DEFINE_PER_CPU(int, y);
    int *x = &__get_cpu_var(y);

    Converts to

    int *x = this_cpu_ptr(&y);

    2. Same as #1 but this time an array structure is involved.

    DEFINE_PER_CPU(int, y[20]);
    int *x = __get_cpu_var(y);

    Converts to

    int *x = this_cpu_ptr(y);

    3. Retrieve the content of the current processors instance of a per cpu
    variable.

    DEFINE_PER_CPU(int, y);
    int x = __get_cpu_var(y)

    Converts to

    int x = __this_cpu_read(y);

    4. Retrieve the content of a percpu struct

    DEFINE_PER_CPU(struct mystruct, y);
    struct mystruct x = __get_cpu_var(y);

    Converts to

    memcpy(&x, this_cpu_ptr(&y), sizeof(x));

    5. Assignment to a per cpu variable

    DEFINE_PER_CPU(int, y)
    __get_cpu_var(y) = x;

    Converts to

    this_cpu_write(y, x);

    6. Increment/Decrement etc of a per cpu variable

    DEFINE_PER_CPU(int, y);
    __get_cpu_var(y)++

    Converts to

    this_cpu_inc(y)

    Signed-off-by: Christoph Lameter
    Signed-off-by: Jens Axboe

    Christoph Lameter
     

15 Jul, 2013

1 commit

  • 0b776b062   block: delete __cpuinit usage from all block files ... Browse Code »

    The __cpuinit type of throwaway sections might have made sense
    some time ago when RAM was more constrained, but now the savings
    do not offset the cost and complications. For example, the fix in
    commit 5e427ec2d0 ("x86: Fix bit corruption at CPU resume time")
    is a good example of the nasty type of bugs that can be created
    with improper use of the various __init prefixes.

    After a discussion on LKML[1] it was decided that cpuinit should go
    the way of devinit and be phased out. Once all the users are gone,
    we can then finally remove the macros themselves from linux/init.h.

    This removes all the drivers/block uses of the __cpuinit macros
    from all C files.

    [1] https://lkml.org/lkml/2013/5/20/589

    Cc: Jens Axboe
    Signed-off-by: Paul Gortmaker

    Paul Gortmaker
     

04 Dec, 2009

1 commit

  • af901ca18   tree-wide: fix assorted typos all over the place ... Browse Code »

    That is "success", "unknown", "through", "performance", "[re|un]mapping"
    , "access", "default", "reasonable", "[con]currently", "temperature"
    , "channel", "[un]used", "application", "example","hierarchy", "therefore"
    , "[over|under]flow", "contiguous", "threshold", "enough" and others.

    Signed-off-by: André Goddard Rosa
    Signed-off-by: Jiri Kosina

    André Goddard Rosa
     

11 Sep, 2009

5 commits