Messages in this thread | | | From | Rob Landley <> | Subject | Re: OOM killer gripe (was Re: What still uses the block layer?) | Date | Tue, 16 Oct 2007 18:59:54 -0500 |
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On Tuesday 16 October 2007 5:28:59 am Alan Cox wrote: > > I'm sure somebody will eventually write an OLS paper or something on the > > advisability of making swapping decisions with 4k granularity when disks > > really want bigger I/O transactions. > > Funnily enough someone thought of that many years ago. They even added > and documented it, then they made it adjustable. > > See the vm section of Documentation/filesystems/proc.txt
I presume you refer to:
page-cluster ------------
page-cluster controls the number of pages which are written to swap in a single attempt. The swap I/O size.
It is a logarithmic value - setting it to zero means "1 page", setting it to 1 means "2 pages", setting it to 2 means "4 pages", etc.
The default value is three (eight pages at a time). There may be some small benefits in tuning this to a different value if your workload is swap-intensive.
I didn't know that controlled whether the pages were contiguous (or written to contiguous locations in swap). I thought it was just how many the VM tried to free at a time.
Still, worth a tweak. Thanks.
> Alan
Rob -- "One of my most productive days was throwing away 1000 lines of code." - Ken Thompson. - 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/
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