Re: VM/IO performance sucks in 2.3.99-pre6

From: Jeff V. Merkey (jmerkey@timpanogas.com)
Date: Wed May 03 2000 - 13:35:45 EST


Sounds like Rik has a good handle on this. I'm certain he'll have us a
fix out fairly quickly.

:-)

Jeff

Richard Gooch wrote:
>
> Jeff V. Merkey writes:
> >
> > Dirty pages should be flushed as fast as possible (they should become
> > eligible after 2 seconds to being flushed out to disk). Pre-6 does have
> > some problems.
> > >
> > > Hi, all. I know there's been grumbling about VM/IO/LRU's/page aging
> > > recently. To give an idea of how bad it is:
> > >
> > > I have a drive that is capable of delivering >12 MB/s. By using dd on
> > > the block device (reading in more data than I have RAM), I quickly get
> > > to a state where I'm getting << 1 MB/s. My guess is that I'm getting
> > > 100 kB/s or less. Once this happens, it seems easiest to reboot to
> > > bring things back to a sane state.
> > >
> > > It seems the current LRU algorithm is "Least Recently Used pages will
> > > remain in RAM the longest". I'd call that a BFULRU.
>
> These pages aren't dirty. I was doing
> # time dd if=$device of=/dev/null bs=1024k
>
> Regards,
>
> Richard....
> Permanent: rgooch@atnf.csiro.au
> Current: rgooch@ras.ucalgary.ca
>
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