lkml.org 
[lkml]   [2004]   [Mar]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: 2.6.4-mm2
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/

\
 
 \ /
  Last update: 2005-03-22 14:01    [W:0.276 / U:0.152 seconds]
©2003-2014 Jasper Spaans. Advertise on this site