Messages in this thread | | | Subject | Re: [PATCH] slub: prefetch next freelist pointer in slab_alloc() | From | Eric Dumazet <> | Date | Fri, 16 Dec 2011 18:18:35 +0100 |
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Le vendredi 16 décembre 2011 à 10:31 -0600, Christoph Lameter a écrit : > On Fri, 16 Dec 2011, Eric Dumazet wrote: > > > Recycling a page is a problem, since freelist link chain is hot on > > cpu(s) which freed objects, and possibly very cold on cpu currently > > owning slab. > > Good idea. How do the tcp benchmarks look after this? > > Looks sane. > > Acked-by: Christoph Lameter <cl@linux.com>
Thanks !
I wouldnt expect TCP being a huge win (most of cpu is consumed in tcp stack, not really memory allocations), but still...
[I expect much better gain on an UDP load, where memory allocator costs are higher ]
$ cat netperf.sh for in in `seq 1 32` do netperf -H 192.168.20.110 -v 0 -l -100000 -t TCP_RR & done wait
If cpu0 handles network interrupts, and other cpus run applications :
Before
Performance counter stats for './netperf.sh':
38001,927957 task-clock # 2,344 CPUs utilized 3 306 138 context-switches # 0,087 M/sec 79 CPU-migrations # 0,000 M/sec 9 656 page-faults # 0,000 M/sec 83 564 329 446 cycles # 2,199 GHz 61 350 744 867 stalled-cycles-frontend # 73,42% frontend cycles idle 34 907 541 687 stalled-cycles-backend # 41,77% backend cycles idle 44 739 971 752 instructions # 0,54 insns per cycle # 1,37 stalled cycles per insn 8 662 005 669 branches # 227,936 M/sec 249 555 153 branch-misses # 2,88% of all branches
16,214220448 seconds time elapsed
After :
Performance counter stats for './netperf.sh':
37035,347847 task-clock # 2,374 CPUs utilized 3 314 540 context-switches # 0,089 M/sec 131 CPU-migrations # 0,000 M/sec 9 691 page-faults # 0,000 M/sec 81 783 678 294 cycles # 2,208 GHz 59 595 242 695 stalled-cycles-frontend # 72,87% frontend cycles idle 34 367 813 304 stalled-cycles-backend # 42,02% backend cycles idle 44 698 853 546 instructions # 0,55 insns per cycle # 1,33 stalled cycles per insn 8 654 940 308 branches # 233,694 M/sec 245 578 562 branch-misses # 2,84% of all branches
15,597940419 seconds time elapsed
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