[lkml]   [2006]   [Mar]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH] mm: yield during swap prefetching
On Thu, 9 Mar 2006 01:22 pm, Nick Piggin wrote:
> Pavel Machek wrote:
> >On Út 07-03-06 16:05:15, Andrew Morton wrote:
> >>Why do you want that?
> >>
> >>If prefetch is doing its job then it will save the machine from a pile of
> >>major faults in the near future. The fact that the machine happens
> >
> >Or maybe not.... it is prefetch, it may prefetch wrongly, and you
> >definitely want it doing nothing when system is loaded.... It only
> >makes sense to prefetch when system is idle.
> Right. Prefetching is obviously going to have a very low work/benefit,
> assuming your page reclaim is working properly, because a) it doesn't
> deal with file pages, and b) it is doing work to reclaim pages that
> have already been deemed to be the least important.
> What it is good for is working around our interesting VM that apparently
> allows updatedb to swap everything out (although I haven't seen this
> problem myself), and artificial memory hogs. By moving work to times of
> low cost. No problem with the theory behind it.
> So as much as a major fault costs in terms of performance, the tiny
> chance that prefetching will avoid it means even the CPU usage is
> questionable. Using sched_yield() seems like a hack though.

Yeah it's a hack alright. Funny how at last I find a place where yield does
exactly what I want and because we hate yield so much noone wants me to use
it all.

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: 2006-03-09 03:32    [W:0.117 / U:16.968 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site