CVS commit: src/sys/dev

[Thor Lancelot Simon <tls%netbsd.org@localhost>]

Module Name:    src
Committed By:   tls
Date:           Mon Mar 22 17:30:33 UTC 2004

Modified Files:
        src/sys/dev: ld.c

Log Message:
Don't use BUFQ_FCFS.  It degrades performance both for "smart" (Mylex
ExtremeRAID with NV cache) and "dumb" (3ware 6410) ld providers.

Instead, use the default buffer queue policy.

With the 3ware adapter, using the read priority strategy instead of FCFS,
for three extractions of pkgsrc, took 329 seconds instead of 331 -- but
with a dramatic improvement in perceived system response (latency for
I/O outside the main stream).

With the Mylex adapter, the improvement was dramatic: using read priority
instead of FCFS yielded an improvement from 381 seconds to 135 seconds!
There was a less-noticeable improvement in perceived latency as well.

The other disk drivers currently hard-wired to FCFS or another policy
should probably be changed as well.


To generate a diff of this commit:
cvs rdiff -r1.26 -r1.27 src/sys/dev/ld.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.