From: Junio C Hamano <gitster@pobox.com>
To: "Utsav Shah via GitGitGadget" <gitgitgadget@gmail.com>
Cc: git@vger.kernel.org, Utsav Shah <ukshah2@illinois.edu>,
Utsav Shah <utsav@dropbox.com>
Subject: Re: [PATCH 1/1] unpack-trees: skip lstat based on fsmonitor
Date: Mon, 28 Oct 2019 12:37:06 +0900 [thread overview]
Message-ID: <xmqq8sp5a6cd.fsf@gitster-ct.c.googlers.com> (raw)
In-Reply-To: <609c7c5047719a619ba22425dafc6ecd105e2cda.1572017008.git.gitgitgadget@gmail.com> (Utsav Shah via GitGitGadget's message of "Fri, 25 Oct 2019 15:23:28 +0000")
"Utsav Shah via GitGitGadget" <gitgitgadget@gmail.com> writes:
> From: Utsav Shah <utsav@dropbox.com>
>
> git stash runs git reset --hard as its final step, which can be fairly slow on a large repository.
> This change lets us skip that if fsmonitor thinks those files aren't modified.
>
> git stash goes from ~8s -> 2s on my repository after this change.
Please line-wrap overlong lines.
More importantly, "stash" may be a mere symptom that does not
deserve this much emphasis. What you improved directly is "git
reset --hard" isn't it?
The fsmonitor may know that a path hasn't been modified but
"git reset --hard" did not pay attention to it and performed
its own check based on ie_match_stat(), which was inefficient.
or something like that?
> if (old && same(old, a)) {
> int update = 0;
> - if (o->reset && o->update && !ce_uptodate(old) && !ce_skip_worktree(old)) {
> + if (o->reset && o->update && !ce_uptodate(old) && !ce_skip_worktree(old) &&
> + !(old->ce_flags & CE_FSMONITOR_VALID)) {
I wonder if !ce_uptodate(old) should say "this one is up to date and
not modified" when CE_FSMONITOR_VALID bit is set. Are there other
codepaths that use ce_uptodate(ce) to decide to do X without paying
attention to CE_FSMONITOR_VALID bit? If there are, are they buggy
in the same way as you found this instance, or do they have legitimate
reason why they only check ce_uptodate(ce) and ignore fsmonitor?
If there isn't, would it make sense to get rid of CE_FSMONITOR_VALID
bit and have fsmonitor directly set CE_UPTODATE bit instead? That
would make this fix unnecessary and fix other codepaths that check
only ce_uptodate() without checking fsmonitor.
next prev parent reply other threads:[~2019-10-28 3:37 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-25 15:23 [PATCH 0/1] unpack-trees: skip lstat on files based on fsmonitor Utsav Shah via GitGitGadget
2019-10-25 15:23 ` [PATCH 1/1] unpack-trees: skip lstat " Utsav Shah via GitGitGadget
2019-10-28 3:37 ` Junio C Hamano [this message]
2019-10-28 6:39 ` Utsav Shah
2019-10-28 19:23 ` Kevin Willford
2019-10-29 19:06 ` Utsav Shah
2019-10-29 20:12 ` Kevin Willford
2019-10-29 23:50 ` Utsav Shah
2019-10-30 0:21 ` Junio C Hamano
2019-10-30 16:41 ` Utsav Shah
2019-11-04 6:02 ` Junio C Hamano
2019-11-05 15:27 ` [PATCH v2 0/1] unpack-trees: skip stat on fsmonitor-valid files Utsav Shah via GitGitGadget
2019-11-05 15:27 ` [PATCH v2 1/1] " Utsav Shah via GitGitGadget
2019-11-05 21:40 ` Kevin Willford
2019-11-06 4:36 ` Utsav Shah
2019-11-06 17:24 ` Kevin Willford
2019-11-06 4:54 ` [PATCH v3 0/1] " Utsav Shah via GitGitGadget
2019-11-06 4:54 ` [PATCH v3 1/1] " Utsav Shah via GitGitGadget
2019-11-06 10:46 ` Junio C Hamano
2019-11-06 22:33 ` Utsav Shah
2019-11-08 3:51 ` Utsav Shah
2019-11-08 4:11 ` Junio C Hamano
2019-11-06 10:16 ` [PATCH v3 0/1] " Junio C Hamano
2019-11-20 8:32 ` [PATCH v4 " Utsav Shah via GitGitGadget
2019-11-20 8:32 ` [PATCH v4 1/1] " Utsav Shah via GitGitGadget
2019-11-21 4:15 ` Junio C Hamano
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