* [linux-lvm] heat map
@ 2013-06-24 7:04 matthew patton
2013-06-24 19:24 ` Alasdair G Kergon
0 siblings, 1 reply; 2+ messages in thread
From: matthew patton @ 2013-06-24 7:04 UTC (permalink / raw)
To: linux-lvm
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.
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [linux-lvm] heat map
2013-06-24 7:04 [linux-lvm] heat map matthew patton
@ 2013-06-24 19:24 ` Alasdair G Kergon
0 siblings, 0 replies; 2+ messages in thread
From: Alasdair G Kergon @ 2013-06-24 19:24 UTC (permalink / raw)
To: matthew patton; +Cc: linux-lvm
On Mon, Jun 24, 2013 at 12:04:00AM -0700, matthew patton wrote:
> 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
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