On Fri, Jan 19 2001, Andrea Arcangeli wrote:
> On Thu, Jan 18, 2001 at 03:17:13PM -0200, Marcelo Tosatti wrote:
> > Jens, can be the -blk patch the reason for the slowdown I'm seeing?
>
> This heuristic is way too aggressive:
>
> /*
> * Try to keep 128MB max hysteris. If not possible,
> * use half of RAM
> */
> high_queued_sectors = (total_ram * 2) / 3;
> low_queued_sectors = high_queued_sectors - MB(128);
> if (low_queued_sectors < 0)
> low_queued_sectors = total_ram / 2;
>
> /*
> * for big RAM machines (>= 384MB), use more for I/O
> */
> if (total_ram >= MB(384)) {
> high_queued_sectors = (total_ram * 4) / 5;
> low_queued_sectors = high_queued_sectors - MB(128);
> }
>
> 2/3 of ram locked down in the I/O queue is way too much. 1/3 should be
> ok. big RAM machines needs way less than 1/3 locked down.
Yes I agree, that values should probably be tweaked a bit. I'll
try and squeeze some testing in to generate the best possible
values.
-- * Jens Axboe <axboe@suse.de> * SuSE Labs - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/
This archive was generated by hypermail 2b29 : Tue Jan 23 2001 - 21:00:19 EST