From: ludo@gnu.org (Ludovic Courtès)
To: Christopher Baines <mail@cbaines.net>
Cc: guix-devel@gnu.org
Subject: Re: [PATCH] git-download: Speed up 'git-predicate'.
Date: Wed, 21 Jun 2017 23:17:02 +0200 [thread overview]
Message-ID: <87shitghwx.fsf@gnu.org> (raw)
In-Reply-To: <ccd33471-7990-df46-a460-0dac9f5ed12c@cbaines.net> (Christopher Baines's message of "Mon, 19 Jun 2017 08:24:24 +0100")
Hi!
Christopher Baines <mail@cbaines.net> skribis:
> On 07/06/17 13:52, Ludovic Courtès wrote:
>> Christopher Baines <mail@cbaines.net> skribis:
[...]
>> Do you know how much the inode optimization vs. the tree structure
>> contributes to the performance.
>
> I've got some more data. I ran the test script for smart-answers, and
> let it complete this time:
>
> real 97m21.291s
> user 120m50.400s
> sys 0m31.020s
>
> Just applying the inode optimization gives this result:
>
> real 90m28.116s
> user 100m44.784s
> sys 0m18.524s
>
> I'm going to assume that using the tree structure for directories makes
> up the rest of the difference. This will vary between repositories
> though, I think smart answers has a unusually large directory to file ratio.
Interesting, thanks for benchmarking!
>> Likewise, the (map car …) call for ‘match’. :-)
>
> I'm stuck on this bit though, in the latest patch it reads:
>
> (list? (member top-directory (map car tree))
>
> The list? call is just to turn the list or #f returned by member to #t
> or #f. The (map car tree) converts the tree to a list of top level
> directories. This bit of code is used when the last directory in the
> input list has been reached (e.g. when checking for foo/bar/baz
> top-directory would be baz) so the last check to perform is to check if
> baz exists at the current level of the tree. Any suggestions on
> restructuring this?
Probably:
(match tree
(((heads . _) ...)
(->bool (member top-directory heads))))
>>> + (inodes-vhash (alist->vhash
>>> + (map
>>> + (lambda (file)
>>> + (let ((stat
>>> + (lstat (string-append directory "/" file))))
>>> + (cons (stat:ino stat) (stat:dev stat))))
>>> + files)))
>>
>> I would call it ‘inodes’ simply. Also, we could use ‘list->set’ from
>> (guix sets) here.
>
> I've made the inodes-vhash -> inodes rename, but I was undecided about
> using (guix sets), is there a reason you recommended it?
Because conceptually it’s a set: what we want to know is whether the set
contains a given inode/device pair.
I’ll comment on v2 of the patch.
Thank you,
Ludo’.
prev parent reply other threads:[~2017-06-21 21:17 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-02 7:08 [PATCH] git-download: Speed up 'git-predicate' Christopher Baines
2017-06-02 7:34 ` Christopher Baines
2017-06-07 12:40 ` Ludovic Courtès
2017-06-07 18:12 ` Christopher Baines
2017-06-07 12:52 ` Ludovic Courtès
2017-06-08 20:43 ` Christopher Baines
2017-06-19 7:14 ` Christopher Baines
2017-06-21 21:44 ` Ludovic Courtès
2017-07-16 10:42 ` Christopher Baines
2017-07-25 21:26 ` Ludovic Courtès
2017-07-26 9:58 ` Christopher Baines
2017-06-19 7:24 ` Christopher Baines
2017-06-21 21:17 ` Ludovic Courtès [this message]
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