[lkml]   [2004]   [Oct]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: Page cache write performance issue
Nick Piggin <> wrote:
> Andrew probably has better ideas.

uh, is this an ia32 highmem box?

If so, you've hit the VM sour spot. That 128M highmem zone gets 100%
filled with dirty pages and we end up doing a ton of writeout off the page
LRU. And we do that while `dd' is cheerfully writing to a totally
different part of the disk via balance_dirty_pages(). Seekstorm ensues.
Although last time I looked (a long time ago) the slowdown was only 2:1 -
perhaps your disk is in writethrough mode??

Basically, *any* other config is fine. 896MB and below, 1.5GB and above.

I could well understand that a minor kswapd tweak would make this bad
situation worse. Making the dirty ratios really small (dirty_ratio less
than the 128MB) should make it go away.

If it's not ia32 then dunno.
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2005-03-22 14:07    [W:0.044 / U:2.440 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site