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From: Jonathan Tan <jonathantanmy@google.com>
To: jonathantanmy@google.com
Cc: git@vger.kernel.org
Subject: Re: [PATCH 2/2] cache-tree: prefetch in partial clone read-tree
Date: Fri, 23 Jul 2021 11:55:48 -0700	[thread overview]
Message-ID: <20210723185548.1784350-1-jonathantanmy@google.com> (raw)
In-Reply-To: <f4881b7455b9d33c8a53a91eda7fbdfc5d11382c.1627066238.git.jonathantanmy@google.com>

> "git read-tree" checks the existence of the blobs referenced by the
> given tree, but does not bulk prefetch them. Add a bulk prefetch.
> 
> The lack of prefetch here was noticed at $DAYJOB during a merge
> involving some specific commits, but I couldn't find a minimal merge
> that didn't also trigger the prefetch in check_updates() in
> unpack-trees.c (and in all these cases, the lack of prefetch in
> cache-tree.c didn't matter because all the relevant blobs would have
> already been prefetched by then). This is why I used read-tree here to
> exercise this code path.
> 
> Signed-off-by: Jonathan Tan <jonathantanmy@google.com>

Forgot to mention: the $DAYJOB case is the same case as in [1]. In [1] I
noticed that the object wasn't actually being used, so I disabled the
object existence check. But that's probably the wrong approach - if the
caller really didn't want the object's existence to be checked, they
could have used WRITE_TREE_MISSING_OK when calling cache_tree_update().

[1] https://lore.kernel.org/git/cover.1627066238.git.jonathantanmy@google.com/

  reply	other threads:[~2021-07-23 18:55 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-23 18:52 [PATCH 0/2] Another partial clone prefetch Jonathan Tan
2021-07-23 18:52 ` [PATCH 1/2] unpack-trees: refactor prefetching code Jonathan Tan
2021-07-23 20:26   ` Elijah Newren
2021-07-23 18:52 ` [PATCH 2/2] cache-tree: prefetch in partial clone read-tree Jonathan Tan
2021-07-23 18:55   ` Jonathan Tan [this message]
2021-07-23 21:20   ` Junio C Hamano
2021-07-23 21:34   ` Elijah Newren
2021-07-26 13:01 ` [PATCH 0/2] Another partial clone prefetch Derrick Stolee

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