[dm-devel] [PATCHES]: dm lock optimization
Jun'ichi Nomura
j-nomura at ce.jp.nec.com
Thu Apr 19 05:17:14 UTC 2012
Hello Mikulas,
On 04/19/12 12:03, Mikulas Patocka wrote:
> http://people.redhat.com/mpatocka/patches/kernel/dm-lock-optimization/
>
> The patches remove cache-line bouncing from device mapper when multiple
> processors submit requests simultaneously.
I think the idea of optimization is nice.
>From a quick look, however, I have some comments:
dm-optimize-no-irqsave-map-lock.patch:
- dm_get_live_table() is called from request_fn,
that can be called from in_interrupt context.
So the added BUG_ON will be triggered.
dm-optimize-percpu-io-lock.patch:
- The following existing mechanisms could be used:
* include/linux/rcupdate.h
* include/linux/lglock.h
(or extended if necessary).
dm-optimize-get_live_table_fast.patch:
- dm_lld_busy() can (theoretically, if dm-mpath is stacked)
be called from in_interrupt context and trigger the
BUG_ON.
--
Jun'ichi Nomura, NEC Corporation
More information about the dm-devel
mailing list