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markw@osdl.org wrote: > > Sorry I'm falling behind... I see about a 10% decrease in throughput > with our dbt2 workload when comparing 2.6.4-mm2 to 2.6.3. I'm wondering > if this might be a result of the changes to the pagecache, radix-tree > and writeback code since you mentioned it could affect i/o scheduling in > 2.6.4-mm1. Could be. Have you run tests without LVM in the picture? > PostgreSQL is using 8KB blocks and the characteristics of the i/o should > be that one lvm2 volume is experiencing mostly sequential writes, while > another has random reading and writing. Both these volumes are using > ext2. I'll summarize the throughput results here, with the lvm2 stripe > width varying across the columns: > > kernel 16 kb 32 kb 64 kb 128 kb 256 kb 512 kb > 2.6.3 2308 2335 2348 2334 > 2.6.4-mm2 2028 2048 2074 2096 2082 2078 > > Here's a page with links to profile, oprofile, etc of each result: > http://developer.osdl.org/markw/linux/2.6-pagecache.html > > Comparing one pair of readprofile results, I find it curious that > dm_table_unplug_all and dm_table_any_congested show up near the top of a > 2.6.4-mm2 profile when they haven't shown up before in 2.6.3. 14015190 poll_idle 241641.2069 175162 generic_unplug_device 1317.0075 165480 __copy_from_user_ll 1272.9231 161151 __copy_to_user_ll 1342.9250 152106 schedule 85.0705 142395 DAC960_LP_InterruptHandler 761.4706 113677 dm_table_unplug_all 1386.3049 65420 __make_request 45.5571 64832 dm_table_any_congested 697.1183 37913 try_to_wake_up 32.2939 That's broken. How many disks are involve in the DM stack? The relevant code was reworked subsequent to 2.6.4-mm2. Maybe we fixed this, but I cannot immediately explain what you're seeing here. - 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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