Messages in this thread | | | Date | Thu, 31 Oct 2002 16:23:30 +0530 | From | Dipankar Sarma <> | Subject | Re: dcache_rcu [performance results] |
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On Wed, Oct 30, 2002 at 04:19:12PM +0530, Maneesh Soni wrote: > Hello Viro, > > Please consider forwarding the following patch ito Linus for dcache lookup > using Read Copy Update. The patch has been there in -mm kernel since > 2.5.37-mm1. The patch is stable. A couple of bugs reported are solved. It > helps a great deal on higher end SMP machines and there is no performance > regression on UP and lower end SMP machines as seen in Dipankar's kernbench > numbers. > > http://marc.theaimsgroup.com/?l=linux-kernel&m=103462075416638&w=2 >
Anton (Blanchard) did some benchmarking with this in a 24-way ppc64 box and the results showed why we need this patch. Here are some performace comparisons based on a multi-user benchmark that Anton ran with vanilla 2.5.40 and 2.5.40-mm.
http://lse.sourceforge.net/locking/dcache/summary.png
base = 2.5.40 base-nops = 2.5.40 but ps command in benchmark scripts commented out mm = 2.5.40-mm mm-nops = 2.5.40-mm but ps command in benchmark scripts commented out
Here is a profile output snippet of base and mm runs at 200 scripts -
base :
Hits Percentage Function ------------------------ 75185 100.00 total 11215 14.92 path_lookup 8578 11.41 atomic_dec_and_lock 5763 7.67 do_lookup 5745 7.64 proc_pid_readlink 4344 5.78 page_remove_rmap 2144 2.85 page_add_rmap 1587 2.11 link_path_walk 1531 2.04 proc_check_root 1461 1.94 save_remaining_regs 1345 1.79 inode_change_ok 1236 1.64 ext2_free_blocks 1215 1.62 ext2_new_block 1067 1.42 d_lookup 1053 1.40 number 907 1.21 release_pages
mm :
Hits Percentage Function 62369 100.00 total 5802 9.30 page_remove_rmap 4092 6.56 atomic_dec_and_lock 3887 6.23 proc_pid_readlink 3207 5.14 follow_mount 2979 4.78 page_add_rmap 2066 3.31 save_remaining_regs 1856 2.98 d_lookup 1629 2.61 number 1235 1.98 release_pages 1168 1.87 pSeries_flush_hash_range 1154 1.85 do_page_fault 1026 1.65 copy_page 1009 1.62 path_lookup
Thanks -- Dipankar Sarma <dipankar@in.ibm.com> http://lse.sourceforge.net Linux Technology Center, IBM Software Lab, Bangalore, India. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.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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