From: Rik van Riel <H.H.vanRiel@fys.ruu.nl>
To: Noel Maddy <ncm@biostat.hfh.edu>
Cc: linux-mm <linux-mm@kvack.org>
Subject: Re: mmap-age patch, comments wanted
Date: Mon, 22 Dec 1997 23:14:33 +0100 (MET) [thread overview]
Message-ID: <Pine.LNX.3.91.971222230403.15190B-100000@mirkwood.dummy.home> (raw)
In-Reply-To: <m0xkBUW-000sMBC@linux.biostat.hfh.edu>
On Mon, 22 Dec 1997, Noel Maddy wrote:
> That was definitely the case with your older vhand patches -- with
> them, I could get about 20M more into virtual memory before
> performance started degrading. What I'm seeing now is a change in
> performance at the same load level. I'm not sure whether the overall
> performance is hurt, because the vanilla kernel thrashes a lot in the
> same situation, but the system remains responsive. It could be that
> the load takes longer in the vanilla kernel (I'll try to check that
> today), but the lack of responsiveness with the mmap-age patch makes
> it *seem* slower.
With vhand, the kernel didn't properly age user-pages, so
swap usage was overly high compared to vanilla or mmap-age,
so comparing swap usage is no good indication of system load.
Also, between vanilla and mmap-age, the mmap-age patched kernel
uses swap more than the vanilla one. But the difference should
be very small, so swap usage should still be usable as an
indication for VM load.
I think that what's really making things slower, is that kswapd
now has to scan more pages before it can swap one out. This
makes the swapout slower (as MAX_SWAP_FAIL still is set at 3)
so there are less free pages left to swap things in again.
I'm going to try to resolve this issue right now...
Rik.
+-----------------------------+------------------------------+
| For Linux mm-patches, go to | "I'm busy managing memory.." |
| my homepage (via LinuxHQ). | H.H.vanRiel@fys.ruu.nl |
| ...submissions welcome... | http://www.fys.ruu.nl/~riel/ |
+-----------------------------+------------------------------+
next parent reply other threads:[~1997-12-23 1:05 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <m0xkBUW-000sMBC@linux.biostat.hfh.edu>
1997-12-22 22:14 ` Rik van Riel [this message]
[not found] <m0xjTGa-000sLKC@linux.biostat.hfh.edu>
1997-12-22 16:29 ` Rik van Riel
1997-12-19 11:50 Rik van Riel
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