Hello On Fri, Sep 22, 2017 at 07:31:29PM +0200, Greg KH wrote: > On Fri, Sep 22, 2017 at 10:16:06AM -0700, Eduardo Valentin wrote: > > Hello GregKH, > > > > I have been seeing several reports of performance issue with raid0 while performing fstrim on v4.9.y. > > Currently, if one performs: > > > > # fio --name fio_test_file --direct=1 --rw=randwrite --bs=4k --size=5G --numjobs=8 --group_reporting --directory=/mount/raid0 > > # rm -rf /media/nvme-raid0 > > # time fstrim -vvv -a > > real 3m41.102s > > user 0m0.000s > > sys 0m4.964s > > > > And on latest linus master, in fact, starting v4.12, we get > > > > # time fstrim -vvv -a > > /mount/raid0: 3.5 TiB (3798132523008 bytes) trimmed > > > > real 0m1.953s > > user 0m0.004s > > sys 0m0.004s > > > > So, I performed a git bisect and found this patch: > > commit 29efc390b9462582ae95eb9a0b8cd17ab956afc0 > > Author: Shaohua Li <shli@xxxxxx> > > Date: Sun May 7 17:36:24 2017 -0700 > > > > md/md0: optimize raid0 discard handling > > > > However, the above patch depends on several other patches. I have performed a backport of the depending patches and I confirm > > I can get the performance boost after applying all fixes. The list of patches is bellow. I also have a branch with the backports > > here: > > > > https://git.kernel.org/pub/scm/linux/kernel/git/evalenti/linux.git/log/?h=backports/v4.9.y/raid0/fstrim > > > > > > And here is the list of patches: > > 797476b block: Add 'zoned' queue limit > > c4aebd0 block: remove bio_is_rw > > bd1c1c2 block: REQ_NOMERGE is common to the bio and request > > 188bd2b block: move REQ_RAHEAD to common flags > > 8d2bbd4 block: replace REQ_THROTTLED with a bio flag > > e806402 block: split out request-only flags into a new namespace > > ef295ec block: better op and flags encoding > > 8737417 block: add a proper block layer data direction encoding > > e73c23f block: add async variant of blkdev_issue_zeroout > > a6f0788 block: add support for REQ_OP_WRITE_ZEROES > > bef1331 block: don't try to discard from __blkdev_issue_zeroout > > eeeefd4 block: don't try Write Same from __blkdev_issue_zeroout > > 35b785f md: add bad block support for external metadata > > 688834e md/failfast: add failfast flag for md to be used by some personalities. > > 504634f md: add blktrace event for writes to superblock > > 85c9ccd md/bitmap: Don't write bitmap while earlier writes might be in-flight > > 91a6c4a md: wake up personality thread after array state update > > 060b068 md: perform async updates for metadata where possible. > > be306c2 md: define mddev flags, recovery flags and r1bio state bits using enums > > 46533ff md: Use REQ_FAILFAST_* on metadata writes where appropriate > > 6995f0b md: takeover should clear unrelated bits > > 394ed8e md: cleanup mddev flag clear for takeover > > 32cd7cb md/raid5: Use correct IS_ERR() variation on pointer check > > 109e376 md: add block tracing for bio_remapping > > 2648381 md: disable WRITE SAME if it fails in underlayer disks > > 3deff1a md: support REQ_OP_WRITE_ZEROES > > f00d7c8 md/raid0: fix up bio splitting. > > 29efc39 md/md0: optimize raid0 discard handling > > > > The above patches were pulled into the backports due to either static dependency or semantic dependency. > > > > Let me know if it is possible to include these patches into stable v4.9.y. > > That's a lot of patches, I'd like verification from the > maintainers/developers of them that this is ok to do and they have no > objection to it. > I agree here. I copied the original author of the commit that does the fix, and everyone who signed it. I would be glad if maintainers could confirm if these backports make sense. > Otherwise, why not just use 4.13 or 4.14 when it comes out? That is one option when you can deploy new kernels, but the issue still remains in the stable v4.9.y and to whoever is based off that stable kernel. > > thanks, > > greg k-h -- All the best, Eduardo Valentin