heat map
If some older man pages are to be believed there once was a capability to keep a heat map of busy extents. Is there a way to revive that capability? I expect "last I/O within 30 seconds, 5 minute, 15minute" is probably sufficient for most uses as well as summary counters along the same lines.
Quoted 5 lines · matthew patton
If some older man pages are to be believed there once was a capability to keep a heat map of busy extents. Is there a way to revive that capability? I expect "last I/O within 30 seconds, 5 minute, 15minute" is probably sufficient for most uses as well as summary counters along the same lines.
Mikulas is developing a replacement here:
http://people.redhat.com/~mpatocka/patches/kernel/dm-statistics/
Documentation appears at the end of the kernel patch.
If you want to try it out at the moment, you'll need this patch first I think:
http://people.redhat.com/agk/patches/linux/editing/dm-optimize-use-SRCU-and-RCU.patch
Alasdair