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-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
