lkml.org 
[lkml]   [2005]   [Aug]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: process creation time increases linearly with shmem
On Fri, 26 Aug 2005, Ray Fucillo wrote:

> However, there is still a need that the child, once successfully forked, is
> operational reasonably quickly. I suspect that Ross's idea of paging in
> everything after the first fault would not be optimal for us, because we'd
> still be talking about hundreds of ms of work done before the child does
> anything useful.

Simply skipping the page table setup of MAP_SHARED regions
should be enough to fix this issue.

> It would still be far better than the behavior we have today because
> that time would no longer be synchronous with the fork().

Filling in all the page table entries at the first fault to
a VMA doesn't make much sense, IMHO.

The reason I think this is that people have experimented
with prefaulting already resident pages at page fault time,
and those experiments have never shown a conclusive benefit.

Now, if doing such prefaulting for normal processes does not
show a benefit - why would it be beneficial to recently forked
processes with a huge SHM area ?

I suspect we would be better off without that extra complexity,
unless there is a demonstrated benefit to it.

--
All Rights Reversed
-
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/

\
 
 \ /
  Last update: 2005-08-26 19:56    [W:0.079 / U:0.956 seconds]
©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site