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Date: Fri, 14 Mar 2008 13:28:01 +0800 From: "Zhang, Yanmin" <yanmin_zhang@...ux.intel.com> To: Christoph Lameter <clameter@....com> Cc: Andrew Morton <akpm@...ux-foundation.org>, Kay Sievers <kay.sievers@...y.org>, Greg Kroah-Hartman <gregkh@...e.de>, LKML <linux-kernel@...r.kernel.org>, Ingo Molnar <mingo@...e.hu> Subject: Re: hackbench regression since 2.6.25-rc On Fri, 2008-03-14 at 11:30 +0800, Zhang, Yanmin wrote: > 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@...-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 On tigerton, if I add "slub_max_order=3 slub_min_objects=16" to kernel boot cmdline, the result is improved significantly and it takes just 1/10 time of the original testing. Below is the new output of slabino -AD. Name Objects Alloc Free %Fast :0000192 3192 80087199 80084141 92 8 kmalloc-512 773 80016203 80015888 97 9 vm_area_struct 2787 223100 220525 94 17 :0004096 68 118322 118320 99 98 :0000064 12215 123575 111669 98 42 :0000128 4616 53826 49422 97 45 dentry 12373 49568 37286 95 65 :0000080 12823 33755 21206 99 97 So kmalloc-512 is the key. Then, I tested it on stoakley with the same kernel commandline. Improvement is about 50%. One important thing is without the boot parameter, hackbench on stoakey takes only 1/4 time of the one on tigerton. With the boot parameter, hackbench on tigerton is faster than the one on stoakely. Is it possible to initiate slub_min_objects based on possible cpu number? I mean, cpu_possible_map(). We could calculate slub_min_objects by a formular. -yanmin -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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