On Wed, 25 Feb 2015, Mike Snitzer wrote:
On Wed, Feb 25 2015 at 1:17pm -0500,
Busch, Keith <keith.busch@xxxxxxxxx> wrote:
Our first bottleneck appears to be the device mapper's single lock
request queue.
Obviously if we switched dm-multipath over to blk-mq we'd eliminate
that. I'll see how things go and will share any changes I come up
with.
Yes, I'm also looking at blk-mq. It appears conversion helps a lot.
I'm not sure though how many tags or h/w contexts to allocate to ensure
there's enough but not too many. You can't use the underlying device's
blk-tagset count (assuming you could even get to it) since those are
potentially shared among many block devices.
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