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SubjectRe: 2.4 vs 2.2 performance under load comparison
On Thu, 22 Feb 2001, Lars Marowsky-Bree wrote:

> Situation: SAP R/3 + SAP DB + benchmark driver running on a
> single node 4 CPU SMP machine, tuned down to 1GB of RAM.
> Running the SAP benchmark with 75 users on 2.2 yields for the
> first benchmark run:
> - 7018ms average response time
> - 2967s CPU time in 1136s elapsed time
> - ~500MB swap allocated
> - ~1500 pages paged in/s, 268 pages/out/s on average
> Running the same benchmark on 2.4:
> - ~700ms average response time
> - 1884s CPU time in 669s elapsed time
> - ~500MB swap allocated
> - ~50 pages paged in, ~212 pages paged out per second on average

> Rik, it's time for you to break it again *g*

Actually, in 2.4 we have one big VM balancing problem left.

We have no way to auto-balance between refill_inactive_scan()
and swap_out(), so we can (and probably do) still end up paging
out the wrong pages lots of times ... this is alleviated somewhat
by having a 1-second inactive list, but still...

Another problem is a lack of smarter IO clustering, when we get
that better I'm sure we can increase performance even more.


Virtual memory is like a game you can't win;
However, without VM there's truly nothing to lose...

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