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Groups > linux.kernel > #1183782
| From | Jens Axboe <axboe@fb.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 | <pMajD-4ep-17@gated-at.bofh.it> (permalink) |
| References | <pMa0h-3Rk-7@gated-at.bofh.it> <pMa0i-3Rk-15@gated-at.bofh.it> <pMajE-4ep-19@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On 07/14/2015 09:23 AM, Mike Snitzer wrote: > 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. That's true, I should have mentioned that. But if you write a higher value than the device supports, then it will be truncated to the max value that the device supports. So it's not really lost, and it was the best alternative I could think of. -- Jens Axboe -- 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/
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[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
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