Remove zfs_vdev_elevator module option #9609
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As described in commit f81d5ef the zfs_vdev_elevator module option is being removed. Users who require this functionality should update their systems to set the disk scheduler using a udev rule. Signed-off-by: Brian Behlendorf <[email protected]>
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Code-wise, this looks fine to me.
Do we have any idea what the trade-offs are, performance-wise, between the noop/none schedulers and whatever is the default (deadline, I think)? I thought the reason this was originally implemented was to avoid ZFS's I/O scheduler and the kernel I/O scheduler fighting each other (or at a minimum, the latter just wasting effort for no gain).
Put differently, you said "if users"... is this something that only some users need to customize, or is this something that most people would want? If it's the latter, then I think we should ship such a udev rule by default.
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Historically using the kernel's These days Regardless, I did look in to adding a udev rule we could ship. Doing so it a bit more complicated than you'd expect since there is no one right answer for what it should be set to. For example, on a CentOS 7 system running a 3.10 kernel with traditional HDDs the available options are: While when running a 5.3 and using virtual vd device the options are entirely different. I'm sure we could handle this, but given that the defaults are expected to work well I don't think this is something we want to take on any longer. |
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@kpande what mechanism do you use to configure the disk scheduler today to avoid this? |
Codecov Report
@@ Coverage Diff @@
## master #9609 +/- ##
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+ Coverage 79.19% 79.21% +0.01%
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Files 418 418
Lines 123531 123499 -32
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- Hits 97828 97826 -2
+ Misses 25703 25673 -30
Continue to review full report at Codecov.
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It sounds like even if we shipped a udev rule for this it wouldn't be of any use. |
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@kpande It might be awesome if you could make it an actually full blown bug report. Because that iscsi target timeout doesn't sound like it's expected/wanted behavior... |
behlendorf
added
Status: Accepted
As described in commit f81d5ef the zfs_vdev_elevator module option is being removed. Users who require this functionality should update their systems to set the disk scheduler using a udev rule. Reviewed-by: Richard Laager <[email protected]> Reviewed-by: loli10K <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Issue openzfs#8664 Closes openzfs#9417 Closes openzfs#9609
As described in commit f81d5ef the zfs_vdev_elevator module option is being removed. Users who require this functionality should update their systems to set the disk scheduler using a udev rule. Reviewed-by: Richard Laager <[email protected]> Reviewed-by: loli10K <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Issue openzfs#8664 Closes openzfs#9417 Closes openzfs#9609
As described in commit f81d5ef the zfs_vdev_elevator module option is being removed. Users who require this functionality should update their systems to set the disk scheduler using a udev rule. Reviewed-by: Richard Laager <[email protected]> Reviewed-by: loli10K <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Issue #8664 Closes #9417 Closes #9609
Motivation and Context
Issue #8664, #9417. Due to issue #9417 we should strongly
consider retiring this feature in the 0.8.x series ahead of schedule.
This change has been planned for master, merging it now allows
us to easily backport it if we decide to do so.
Description
As described in commit f81d5ef the zfs_vdev_elevator module
option is being removed. Users who require this functionality
should update their systems to set the disk scheduler using a
udev rule.
How Has This Been Tested?
Types of changes
Checklist:
Signed-off-by.