Messages in this thread |  | | Date | Wed, 13 Oct 2004 18:15:31 +1000 | From | Nick Piggin <> | Subject | Re: Page cache write performance issue |
| |
Nathan Scott wrote:
>On Wed, Oct 13, 2004 at 12:02:06AM -0700, Andrew Morton wrote: > >>Well something else if fishy: how can you possibly achieve only 4MB/sec? >> > >These are 1K writes too remember, so it feels a bit like we >write 'em out one at a time, sync (though no O_SYNC, or fsync, >or such involved here). This is on an i686, so 4K pages, and >using 4K filesystem blocksizes (both xfs and ext2). > >
Still shouldn't cause such a big slowdown. Seems like they might be getting written off the end of the page reclaim LRU (although in that case it is a bit odd that increasing the dirty thresholds are improving performance).
I don't think we have any vmscan metrics for this... kswapd definitely has become more active in 2.6.9-rc. If you're stuck for ideas, try editing mm/vmscan.c:may_write_to_queue - comment out the if(current_is_kswapd()) check.
It is a long shot though. Andrew probably has better ideas.
- 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/
|  |