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  1. 18 5月, 2010 36 次提交
  3. 17 5月, 2010 4 次提交
    • A
      perf tui: Add workaround for slang < 2.1.4 · dc4ff193
      由 Arnaldo Carvalho de Melo 提交于 
      Older versions of the slang library didn't used the 'const' specifier,
causing problems with modern compilers of this kind:

util/newt.c:252: error: passing argument 1 of ‘SLsmg_printf’ discards
qualifiers from pointer target type

Fix it by using some wrappers that when needed const the affected
parameters back to plain (char *).
Reported-by: NLin Ming <ming.m.lin@intel.com>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Lin Ming <ming.m.lin@intel.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <20100517145421.GD29052@ghostprotocols.net>
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
      dc4ff193
    • S
      perf record: Fix bug mismatch with -c option definition · 3de29cab
      由 Stephane Eranian 提交于 
      The -c option defines the user requested sampling period. It was implemented
using an unsigned int variable but the type of the option was OPT_LONG. Thus,
the option parser was overwriting memory belonging to other variables, namely
the mmap_pages leading to a zero page sampling buffer. The bug was exposed only
when compiling at -O0, probably because the compiler was padding variables at
higher optimization levels.

This patch fixes this problem by declaring user_interval as u64. This also
avoids wrap-around issues for large period on 32-bit systems.

Commiter note:

Made it use OPT_U64(user_interval) after implementing OPT_U64 in the
previous patch.

Cc: David S. Miller <davem@davemloft.net>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <4bf11ae9.e88cd80a.06b0.ffffa8e3@mx.google.com>
Signed-off-by: NStephane Eranian <eranian@google.com>
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
      3de29cab
    • A
      perf options: Introduce OPT_U64 · 6ba85cea
      由 Arnaldo Carvalho de Melo 提交于 
      We have things like user_interval (-c/--count) in 'perf record' that
needs this.

Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
      6ba85cea
    • A
      atomic_t: Remove volatile from atomic_t definition · 81880d60
      由 Anton Blanchard 提交于 
      When looking at a performance problem on PowerPC, I noticed some awful code
generation:

c00000000051fc98:       3b 60 00 01     li      r27,1
...
c00000000051fca0:       3b 80 00 00     li      r28,0
...
c00000000051fcdc:       93 61 00 70     stw     r27,112(r1)
c00000000051fce0:       93 81 00 74     stw     r28,116(r1)
c00000000051fce4:       81 21 00 70     lwz     r9,112(r1)
c00000000051fce8:       80 01 00 74     lwz     r0,116(r1)
c00000000051fcec:       7d 29 07 b4     extsw   r9,r9
c00000000051fcf0:       7c 00 07 b4     extsw   r0,r0

c00000000051fcf4:       7c 20 04 ac     lwsync
c00000000051fcf8:       7d 60 f8 28     lwarx   r11,0,r31
c00000000051fcfc:       7c 0b 48 00     cmpw    r11,r9
c00000000051fd00:       40 c2 00 10     bne-    c00000000051fd10
c00000000051fd04:       7c 00 f9 2d     stwcx.  r0,0,r31
c00000000051fd08:       40 c2 ff f0     bne+    c00000000051fcf8
c00000000051fd0c:       4c 00 01 2c     isync

We create two constants, write them out to the stack, read them straight back
in and sign extend them. What a mess.

It turns out this bad code is a result of us defining atomic_t as a
volatile int.

We removed the volatile attribute from the powerpc atomic_t definition years
ago, but commit ea435467 (atomic_t: unify all
arch definitions) added it back in.

To dig up an old quote from Linus:

> The fact is, volatile on data structures is a bug. It's a wart in the C
> language. It shouldn't be used.
>
> Volatile accesses in *code* can be ok, and if we have "atomic_read()"
> expand to a "*(volatile int *)&(x)->value", then I'd be ok with that.
>
> But marking data structures volatile just makes the compiler screw up
> totally, and makes code for initialization sequences etc much worse.

And screw up it does :)

With the volatile removed, we see much more reasonable code generation:

c00000000051f5b8:       3b 60 00 01     li      r27,1
...
c00000000051f5c0:       3b 80 00 00     li      r28,0
...

c00000000051fc7c:       7c 20 04 ac     lwsync
c00000000051fc80:       7c 00 f8 28     lwarx   r0,0,r31
c00000000051fc84:       7c 00 d8 00     cmpw    r0,r27
c00000000051fc88:       40 c2 00 10     bne-    c00000000051fc98
c00000000051fc8c:       7f 80 f9 2d     stwcx.  r28,0,r31
c00000000051fc90:       40 c2 ff f0     bne+    c00000000051fc80
c00000000051fc94:       4c 00 01 2c     isync

Six instructions less.
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      81880d60