1. 03 11月, 2014 1 次提交
    • C
      powerpc: Replace __get_cpu_var uses · 69111bac
      Christoph Lameter 提交于
      This still has not been merged and now powerpc is the only arch that does
      not have this change. Sorry about missing linuxppc-dev before.
      
      V2->V2
        - Fix up to work against 3.18-rc1
      
      __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 :
      
      __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)
      
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      CC: Paul Mackerras <paulus@samba.org>
      Signed-off-by: NChristoph Lameter <cl@linux.com>
      [mpe: Fix build errors caused by set/or_softirq_pending(), and rework
            assignment in __set_breakpoint() to use memcpy().]
      Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
      69111bac
  2. 25 9月, 2014 1 次提交
  3. 27 8月, 2014 2 次提交
    • T
      Revert "powerpc: Replace __get_cpu_var uses" · 23f66e2d
      Tejun Heo 提交于
      This reverts commit 5828f666 due to
      build failure after merging with pending powerpc changes.
      
      Link: http://lkml.kernel.org/g/20140827142243.6277eaff@canb.auug.org.auSigned-off-by: NTejun Heo <tj@kernel.org>
      Reported-by: NStephen Rothwell <sfr@canb.auug.org.au>
      Cc: Christoph Lameter <cl@linux-foundation.org>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      23f66e2d
    • C
      powerpc: Replace __get_cpu_var uses · 5828f666
      Christoph Lameter 提交于
      __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)
      
      tj: Folded a fix patch.
          http://lkml.kernel.org/g/alpine.DEB.2.11.1408172143020.9652@gentwo.org
      
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      CC: Paul Mackerras <paulus@samba.org>
      Signed-off-by: NChristoph Lameter <cl@linux.com>
      Signed-off-by: NTejun Heo <tj@kernel.org>
      5828f666
  4. 11 7月, 2014 1 次提交
    • A
      powernv: Add OPAL tracepoints · c49f6353
      Anton Blanchard 提交于
      Knowing how long we spend in firmware calls is an important part of
      minimising OS jitter.
      
      This patch adds tracepoints to each OPAL call. If tracepoints are
      enabled we branch out to a common routine that calls an entry and exit
      tracepoint.
      
      This allows us to write tools that monitor the frequency and duration
      of OPAL calls, eg:
      
      name                  count  total(ms)  min(ms)  max(ms)  avg(ms)  period(ms)
      OPAL_HANDLE_INTERRUPT     5      0.199    0.037    0.042    0.040   12547.545
      OPAL_POLL_EVENTS        204      2.590    0.012    0.036    0.013    2264.899
      OPAL_PCI_MSI_EOI       2830      3.066    0.001    0.005    0.001      81.166
      
      We use jump labels if configured, which means we only add a single
      nop instruction to every OPAL call when the tracepoints are disabled.
      Signed-off-by: NAnton Blanchard <anton@samba.org>
      Acked-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
      Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
      c49f6353