20 Jul
2004
20 Jul
'04
12:33 p.m.
On Tue, Jul 20 2004, Ingo Molnar wrote:
elvtune is long dead :-)
it's not tweakable right now, but if you wish to experiment you just
need to add a line to ide-disk.c:idedisk_setup() - pseudo patch:
+ blk_queue_max_sectors(drive->queue, 32);
+
printk("%s: max request size: %dKiB\n", drive->name,
drive->queue->max_sectors / 2);
/* Extract geometry if we did not already have one for the drive */
above will limit max request to 16kb, experiment as you see fit.
--
Jens Axboe
How much I/O
do you allow to be in flight at once? It seems like by
decreasing the maximum size of I/O that you handle in one interrupt
you could improve this quite a bit. Disk throughput is good enough,
anyone in the real world who would feel a 10% hit would just throw
hardware at the problem.
i'm not sure whether this particular value (max # of sg-entries per IO
op) is runtime tunable. Jens? Might make sense to enable elvtune-alike
tunability of this value.