Re: useless report -- perhaps memory allocation problems in 2.1.12[678]

[Rik van Riel <H.H.vanRiel@phys.uu.nl>]

On Tue, 17 Nov 1998, Linus Torvalds wrote:
> On Tue, 17 Nov 1998, Linus Torvalds wrote:
> > 
> > But whether kswapd should go page-synchronous at some point? Maybe. I can
> > see arguments both for and against (the "for" argument is that we prefer
> > to have more intense bouts of IO followed by a nice clean wait, while the
> > "against" argument is that maybe we want to spread out the thing). 
> 
> Oh, well, I'm currently leaning for "for", which means your patch to
> page_io.c is what I have now.. I don't like "trickling" pages by
> running out of requests or something like that, so having the
> occasional nice wait is probably best. 

It seems like you decided for my point of view before I
woke up again, so I'll just let you know that this is
one of the reasons why I submitted the original (2.1.90?)
patch to you. The other reason was that async, clustered
swapouts have a much higher bandwidth than synchronous
swapouts. This means we can do more swap I/O without
getting into trouble.

The only request I have to make is that you use the
sysctl tuneable limit pager_daemon.swap_cluster as
the limit.  Doing this will enable people to optimize
their kswapd configuration for multiple swap partitions
or disks with loads of tagged queues (or a shortage 
thereoff).

I have found that setting that limit to SWAP_CLUSTER_MAX
* number_of_highest_priority_swap_areas doubled swapout
performance, leaving 50% extra I/O bandwidth for swapins.

cheers,

Rik -- slowly getting used to dvorak kbd layout...
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