On Tue, 2006-06-13 at 13:36 -0600, Lamont R. Peterson wrote: > > Moreover, there isn't a compelling reason *not* to do it. This > > hypothetical performance-while-swapping argument you've got just isn't > > reality. You're not CPU bound when you're swapping. You're I/O > > limited, and most of the limit isn't time on the host bus, it's disk > > seeks. I really doubt if LVM will make any significant difference -- > > measurable difference, that is, much less noticeable by a human -- at > > all. > > Of course. Yes, swapping is not memory or CPU bound, it is I/O bound, as you > state. However, I wasn't talking about LVM code overhead, I was talking > about drive seek overhead in heavy swapping situations. > > If you are doing heavy swapping with a swap partition, the on disk storage is > contiguous and, therefore, you will have less distance to travel when > seeking. That's just as true as on LVM. If I build a LV to put swap on that's comprised of several PVs which aren't contiguous, then sure, it's not contiguous. At the same time, if I make 7 partitions that are 100M each and activate them all, I've got 7 discontiguous areas. In both cases it's "if I set my machine up stupidly, swaping sucks even more than normal". > On LVM, the PEs could be spread around the disk more widely (i.e. > non-contiguous), so the heads will have farther to go. If you're *really* > lucky, your heavy swapping pattern will let you alternate (or rotate, if that > word fits better) around each of the disks with PEs backing your swap LVs > LEs. But, the likelyhood of that working out is very small. It's about as small as actually getting into this contrived situation in the first place... -- Peter -- fedora-devel-list mailing list fedora-devel-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/fedora-devel-list
