bounce buffers and i/o schedulers with aacraid
From: markw
Date: Wed Aug 13 2003 - 18:21:54 EST
We're still trying to avoid bounce buffers with the aacraid driver and
noticed something interesting in some profiles (which I'll copy farther
down) with the deadline scheduler and AS. Using our DBT-2 workload, we
see with the deadline scheduler our patch to avoid bounce buffers
doesn't change the profile much. But with AS, we don't see
bounce_copy_vec or __blk_queue_bounce near the top of the profile. Any
ideas why?
This is with 2.6.0-test3 on a system with 4GB of memory. The first pair
of tables compares the deadline scheduler with our patch applied to the
profile in the right side. The second pair of tables compare AS with
our patch applied to the profile on the right side.
You can see our patch here:
http://www.osdl.org/cgi-bin/getpatch?id=2052
or in color!
http://www.osdl.org/cgi-bin/getpatch?id=2052.html
METRICS OVER LAST 20 MINUTES:
--------------- -------- ----- ---- -------- -----------------------------------
Kernel Elevator NOTPM CPU% Blocks/s URL
--------------- -------- ----- ---- -------- -----------------------------------
2.6.0-test3 deadline 1313 94.5 9582.1 http://khack.osdl.org/stp/277489/
2.6.0-test3 deadline 1304 94.1 9685.0 http://khack.osdl.org/stp/277494/
FUNCTIONS SORTED BY LOAD:
-- ------------------------- ------- ------------------------- -------
# deadline 2.6.0-test3 ticks deadline 2.6.0-test3 ticks
-- ------------------------- ------- ------------------------- -------
1 default_idle 5470223 default_idle 5447766
2 bounce_copy_vec 77961 bounce_copy_vec 85122
3 schedule 65916 schedule 62840
4 __blk_queue_bounce 30048 __blk_queue_bounce 24983
5 do_softirq 23265 scsi_request_fn 23950
6 scsi_request_fn 22748 do_softirq 23573
7 __make_request 18727 __make_request 19055
8 scsi_end_request 12207 scsi_end_request 12358
9 sysenter_past_esp 10296 try_to_wake_up 10007
10 try_to_wake_up 10132 sysenter_past_esp 9959
METRICS OVER LAST 20 MINUTES:
--------------- -------- ----- ---- -------- -----------------------------------
Kernel Elevator NOTPM CPU% Blocks/s URL
--------------- -------- ----- ---- -------- -----------------------------------
2.6.0-test3 as 1143 92.6 8848.5 http://khack.osdl.org/stp/277490/
2.6.0-test3 as 1175 91.4 8883.1 http://khack.osdl.org/stp/277493/
FUNCTIONS SORTED BY LOAD:
-- ------------------------- ------- ------------------------- -------
# as 2.6.0-test3 ticks as 2.6.0-test3 ticks
-- ------------------------- ------- ------------------------- -------
1 default_idle 6089608 default_idle 6307410
2 bounce_copy_vec 69264 schedule 44346
3 schedule 63544 scsi_request_fn 25109
4 scsi_request_fn 25617 __make_request 23740
5 __make_request 23137 do_softirq 20522
6 __blk_queue_bounce 20156 scsi_end_request 15665
7 do_softirq 20012 try_to_wake_up 7979
8 scsi_end_request 15821 dio_bio_end_io 7867
9 sysenter_past_esp 10313 do_anonymous_page 7440
10 try_to_wake_up 9227 ipc_lock 6387
--
Mark Wong - - markw@xxxxxxxx
Open Source Development Lab Inc - A non-profit corporation
12725 SW Millikan Way - Suite 400 - Beaverton, OR 97005
(503) 626-2455 x 32 (office)
(503) 626-2436 (fax)
http://www.osdl.org/archive/markw/
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