Re: [PATCH 2/2] block: make /sys/block/<dev>/queue/discard_max_bytes writeable

From	Mike Snitzer <snitzer@redhat.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH 2/2] block: make /sys/block/<dev>/queue/discard_max_bytes writeable
Date	2015-07-14 17:30 +0200
Message-ID	<pMajE-4ep-19@gated-at.bofh.it> (permalink)
References	<pMa0h-3Rk-7@gated-at.bofh.it> <pMa0i-3Rk-15@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

On Tue, Jul 14 2015 at 11:02am -0400,
Jens Axboe <axboe@fb.com> wrote:

> Lots of devices support huge discard sizes these days. Depending
> on how the device handles them internally, huge discards can
> introduce massive latencies (hundreds of msec) on the device side.
> 
> We have a sysfs file, discard_max_bytes, that advertises the max
> hardware supported discard size. Make this writeable, and split
> the settings into a soft and hard limit. This can be set from
> 'discard_granularity' and up to the hardware limit.

Looks pretty good, but we'll lose the original discard_max_bytes once it
is changed.  That information loss will prevent users from knowing what
adjustments are possible over time.

This may be OK, but figured i'd raise it.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Back to linux.kernel | Previous | Next — Previous in thread | Find similar | Unroll thread

Thread

[PATCH 2/2] block: make /sys/block/<dev>/queue/discard_max_bytes writeable Jens Axboe <axboe@fb.com> - 2015-07-14 17:10 +0200
  Re: [PATCH 2/2] block: make /sys/block/<dev>/queue/discard_max_bytes  writeable Jens Axboe <axboe@fb.com> - 2015-07-14 17:30 +0200
  Re: [PATCH 2/2] block: make /sys/block/<dev>/queue/discard_max_bytes  writeable Mike Snitzer <snitzer@redhat.com> - 2015-07-14 17:30 +0200

csiph-web