Messages in this thread | | | Date | Fri, 11 Dec 2009 12:43:50 +0900 | Subject | Re: [PATCH] vmscan: limit concurrent reclaimers in shrink_zone | From | Minchan Kim <> |
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On Fri, Dec 11, 2009 at 12:19 PM, Rik van Riel <riel@redhat.com> wrote: > On 12/10/2009 09:03 PM, Minchan Kim wrote: > >>> +The default value is 8. >>> + >>> +============================================================= >> >> I like this. but why do you select default value as constant 8? >> Do you have any reason? >> >> I think it would be better to select the number proportional to NR_CPU. >> ex) NR_CPU * 2 or something. >> >> Otherwise looks good to me. > > Pessimistically, I assume that the pageout code spends maybe > 10% of its time on locking (we have seen far, far worse than > this with thousands of processes in the pageout code). That > means if we have more than 10 threads in the pageout code, > we could end up spending more time on locking and less doing > real work - slowing everybody down.
Thanks for giving precious information to me. :
We always have a question magic value with no comment.
Actually I don't want to add another magic value without comment. so I would like to add the your good explanation in change log or as comment on code.
> > I rounded it down to the closest power of 2 to come up with > an arbitrary number that looked safe :) > > However, this number is per zone - I imagine that really large > systems will have multiple memory zones, so they can run with > more than 8 processes in the pageout code simultaneously. > >> Reviewed-by: Minchan Kim<minchan.kim@gmail.com> > > Thank you.
Thanks for quick reply. :)
> -- > All rights reversed. >
-- Kind regards, Minchan Kim -- 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/
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