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SubjectRe: hackbench regression since 2.6.25-rc
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On Fri, 2008-03-14 at 11:04 +0800, Zhang, Yanmin wrote:
> On Thu, 2008-03-13 at 17:16 -0700, Christoph Lameter wrote:
> > Could you recompile the kernel with slub performance statistics and post
> > the output of
> >
> > slabinfo -AD
> Before testing with kernel 2.6.25-rc5:
> Name Objects Alloc Free %Fast
> vm_area_struct 2795 135185 132587 93 29
> :0004096 25 119045 119043 99 98
> :0000064 12257 119671 107742 98 50
> :0000192 3312 78563 75370 92 21
> :0000128 4648 48143 43738 97 53
> dentry 15217 46675 31527 95 72
> :0000080 12784 33674 21206 99 97
> :0000016 4367 25871 23705 99 78
> :0000096 3001 22591 20084 99 92
> buffer_head 5536 18147 12884 97 42
> anon_vma 1729 14948 14130 99 73
>
>
> After testing:
> Name Objects Alloc Free %Fast
> :0000192 3428 80093958 80090708 92 8
> :0000512 374 80016030 80015715 68 7
> vm_area_struct 2875 224524 221868 94 20
> :0000064 12408 134273 122227 98 47
> :0004096 24 127397 127395 99 98
> :0000128 4596 57837 53432 97 48
> dentry 15659 51402 35824 95 64
> :0000016 4584 29327 27161 99 76
> :0000080 12784 33674 21206 99 97
> :0000096 2998 26264 23757 99 93
>
>
> So block 192 and 512's and very active and their fast free percentage is low.
On my 8-core stoakley, there is no such regression. Below data is after testing.

[root@lkp-st02-x8664 ~]# slabinfo -AD
Name Objects Alloc Free %Fast
:0000192 3170 80055388 80052280 92 1
:0000512 316 80012750 80012466 69 1
vm_area_struct 2642 194700 192193 94 16
:0000064 3846 74468 70820 97 53
:0004096 15 69014 69012 98 97
:0000128 1447 32920 31541 91 8
dentry 13485 33060 19652 92 42
:0000080 10639 23377 12953 98 98
:0000096 1662 16496 15036 99 94
:0000832 232 14422 14203 85 10
:0000016 2733 15102 13372 99 14

So the block 192 and 512's fast free percentage is even smaller than the ones on tigerton.

Oprofile data on stoakley:

CPU: Core 2, speed 2660 MHz (estimated)
Counted CPU_CLK_UNHALTED events (Clock cycles when not halted) with a unit mask of 0x00 (Unhalted core cycles) count 100000
samples % app name symbol name
2897265 25.7603 linux-2.6.25-rc5 __slab_alloc
2689900 23.9166 linux-2.6.25-rc5 add_partial
629355 5.5957 linux-2.6.25-rc5 copy_user_generic_string
552309 4.9107 linux-2.6.25-rc5 __slab_free
514792 4.5771 linux-2.6.25-rc5 sock_alloc_send_skb
500879 4.4534 linux-2.6.25-rc5 unix_stream_recvmsg
274798 2.4433 linux-2.6.25-rc5 __kmalloc_track_caller
230283 2.0475 linux-2.6.25-rc5 kfree
222286 1.9764 linux-2.6.25-rc5 unix_stream_sendmsg
217413 1.9331 linux-2.6.25-rc5 memset_c
211589 1.8813 linux-2.6.25-rc5 kmem_cache_alloc
151500 1.3470 linux-2.6.25-rc5 system_call
132262 1.1760 linux-2.6.25-rc5 sock_def_readable
123130 1.0948 linux-2.6.25-rc5 kmem_cache_free
109518 0.9738 linux-2.6.25-rc5 sock_wfree

yanmin




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