On Wed, Apr 14, 2010 at 02:54:14PM +0900, KOSAKI Motohiro wrote:
> > On Wed, Apr 14, 2010 at 01:59:45PM +0900, KAMEZAWA Hiroyuki wrote:
> > > On Wed, 14 Apr 2010 11:40:41 +1000
> > > Dave Chinner <david@xxxxxxxxxxxxx> wrote:
> > >
> > > > 50) 3168 64 xfs_vm_writepage+0xab/0x160 [xfs]
> > > > 51) 3104 384 shrink_page_list+0x65e/0x840
> > > > 52) 2720 528 shrink_zone+0x63f/0xe10
> > >
> > > A bit OFF TOPIC.
> > >
> > > Could you share disassemble of shrink_zone() ?
> > >
> > > In my environ.
> > > 00000000000115a0 <shrink_zone>:
> > > 115a0: 55 push %rbp
> > > 115a1: 48 89 e5 mov %rsp,%rbp
> > > 115a4: 41 57 push %r15
> > > 115a6: 41 56 push %r14
> > > 115a8: 41 55 push %r13
> > > 115aa: 41 54 push %r12
> > > 115ac: 53 push %rbx
> > > 115ad: 48 83 ec 78 sub $0x78,%rsp
> > > 115b1: e8 00 00 00 00 callq 115b6 <shrink_zone+0x16>
> > > 115b6: 48 89 75 80 mov %rsi,-0x80(%rbp)
> > >
> > > disassemble seems to show 0x78 bytes for stack. And no changes to %rsp
> > > until retrun.
> >
> > I see the same. I didn't compile those kernels, though. IIUC,
> > they were built through the Ubuntu build infrastructure, so there is
> > something different in terms of compiler, compiler options or config
> > to what we are both using. Most likely it is the compiler inlining,
> > though Chris's patches to prevent that didn't seem to change the
> > stack usage.
> >
> > I'm trying to get a stack trace from the kernel that has shrink_zone
> > in it, but I haven't succeeded yet....
>
> I also got 0x78 byte stack usage. Umm.. Do we discussed real issue now?
Ok, so here's a trace at the top of the stack from a kernel with a
the above shrink_zone disassembly:
$ cat /sys/kernel/debug/tracing/stack_trace
Depth Size Location (49 entries)
----- ---- --------
0) 6152 112 force_qs_rnp+0x58/0x150
1) 6040 48 force_quiescent_state+0x1a7/0x1f0
2) 5992 48 __call_rcu+0x13d/0x190
3) 5944 16 call_rcu_sched+0x15/0x20
4) 5928 16 call_rcu+0xe/0x10
5) 5912 240 radix_tree_delete+0x14a/0x2d0
6) 5672 32 __remove_from_page_cache+0x21/0x110
7) 5640 64 __remove_mapping+0x86/0x100
8) 5576 272 shrink_page_list+0x2fd/0x5a0
9) 5304 400 shrink_inactive_list+0x313/0x730
10) 4904 176 shrink_zone+0x3d1/0x490
11) 4728 128 do_try_to_free_pages+0x2b6/0x380
12) 4600 112 try_to_free_pages+0x5e/0x60
13) 4488 272 __alloc_pages_nodemask+0x3fb/0x730
14) 4216 48 alloc_pages_current+0x87/0xd0
15) 4168 32 __page_cache_alloc+0x67/0x70
16) 4136 80 find_or_create_page+0x4f/0xb0
17) 4056 160 _xfs_buf_lookup_pages+0x150/0x390
.....
So the differences are most likely from the compiler doing
automatic inlining of static functions...
Cheers,
Dave.
--
Dave Chinner
david@xxxxxxxxxxxxx
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