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From: Martin Fick <mfick@codeaurora.org>
To: git@vger.kernel.org, Julian Phillips <julian@quantumfyre.co.uk>
Subject: Re: Git is not scalable with too many refs/*
Date: Mon, 26 Sep 2011 09:15:29 -0600	[thread overview]
Message-ID: <201109260915.29285.mfick@codeaurora.org> (raw)
In-Reply-To: <201109251443.28243.mfick@codeaurora.org>

OK, I have found what I believe is another performance 
regression for large ref counts (~100K).  

When I run git br on my repo which only has one branch, but 
has ~100K refs under ref/changes (a gerrit repo), it takes 
normally 3-6mins depending on whether my caches are fresh or 
not.  After bisecting some older changes, I noticed that 
this ref seems to be where things start to get slow: 
c774aab98ce6c5ef7aaacbef38da0a501eb671d4


commit c774aab98ce6c5ef7aaacbef38da0a501eb671d4
Author: Julian Phillips <julian@quantumfyre.co.uk>
Date:   Tue Apr 17 02:42:50 2007 +0100

    refs.c: add a function to sort a ref list, rather then 
sorting on add

    Rather than sorting the refs list while building it, 
sort in one
    go after it is built using a merge sort.  This has a 
large
    performance boost with large numbers of refs.

    It shouldn't happen that we read duplicate entries into 
the same
    list, but just in case sort_ref_list drops them if the 
SHA1s are
    the same, or dies, as we have no way of knowing which 
one is the
    correct one.

    Signed-off-by: Julian Phillips 
<julian@quantumfyre.co.uk>
    Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
    Signed-off-by: Junio C Hamano <junkio@cox.net>



which is a bit strange since that commit's purpose was to 
actually speed things up in the case of many refs.  Just to 
verify, I reverted the commit on 1.7.7.rc0.73 and sure 
enough, things speed up down to the 14-20s range depending 
on caching.

If this change does not actually speed things up, should it 
be reverted?  Or was there a bug in the change that makes it 
not do what it was supposed to do?

Thanks,

-Martin

-- 
Employee of Qualcomm Innovation Center, Inc. which is a 
member of Code Aurora Forum

  parent reply	other threads:[~2011-09-26 15:15 UTC|newest]

Thread overview: 126+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-06-09  3:44 Git is not scalable with too many refs/* NAKAMURA Takumi
2011-06-09  6:50 ` Sverre Rabbelier
2011-06-09 15:23   ` Shawn Pearce
2011-06-09 15:52     ` A Large Angry SCM
2011-06-09 15:56       ` Shawn Pearce
2011-06-09 16:26         ` Jeff King
2011-06-10  3:59           ` NAKAMURA Takumi
2011-06-13 22:27             ` Jeff King
2011-06-14  0:17             ` Andreas Ericsson
2011-06-14  0:30               ` Jeff King
2011-06-14  4:41                 ` Junio C Hamano
2011-06-14  7:26                   ` Sverre Rabbelier
2011-06-14 10:02                     ` Johan Herland
2011-06-14 10:34                       ` Sverre Rabbelier
2011-06-14 17:02                       ` Jeff King
2011-06-14 19:20                         ` Shawn Pearce
2011-06-14 19:47                           ` Jeff King
2011-06-14 20:12                             ` Shawn Pearce
2011-09-08 19:53                               ` Martin Fick
2011-09-09  0:52                                 ` Martin Fick
2011-09-09  1:05                                   ` Thomas Rast
2011-09-09  1:13                                     ` Thomas Rast
2011-09-09 15:59                                   ` Jens Lehmann
2011-09-25 20:43                                   ` Martin Fick
2011-09-26 12:41                                     ` Christian Couder
2011-09-26 17:47                                       ` Martin Fick
2011-09-26 18:56                                         ` Christian Couder
2011-09-30 16:41                                           ` Martin Fick
2011-09-30 19:26                                             ` Martin Fick
2011-09-30 21:02                                             ` Martin Fick
2011-09-30 22:06                                               ` Martin Fick
2011-10-01 20:41                                                 ` Junio C Hamano
2011-10-02  5:19                                                   ` Michael Haggerty
2011-10-03  0:46                                                     ` Martin Fick
2011-10-04  8:08                                                       ` Michael Haggerty
2011-10-03 18:12                                                 ` Martin Fick
2011-10-03 19:42                                                   ` Junio C Hamano
2011-10-04  8:16                                                   ` Michael Haggerty
2011-10-08 20:59                                                 ` Martin Fick
2011-10-09  5:43                                                   ` Michael Haggerty
2011-09-28 19:38                                       ` Martin Fick
2011-09-28 22:10                                         ` Martin Fick
2011-09-29  0:54                                           ` Julian Phillips
2011-09-29  1:37                                             ` Martin Fick
2011-09-29  2:19                                               ` Julian Phillips
2011-09-29 16:38                                                 ` Martin Fick
2011-09-29 18:26                                                   ` Julian Phillips
2011-09-29 18:27                                                 ` René Scharfe
2011-09-29 19:10                                                   ` Junio C Hamano
2011-09-29  4:18                                                     ` [PATCH] refs: Use binary search to lookup refs faster Julian Phillips
2011-09-29 21:57                                                       ` Junio C Hamano
2011-09-29 22:04                                                       ` [PATCH v2] " Julian Phillips
2011-09-29 22:06                                                       ` [PATCH] " Junio C Hamano
2011-09-29 22:11                                                         ` [PATCH v3] " Julian Phillips
2011-09-29 23:48                                                           ` Junio C Hamano
2011-09-30 15:30                                                             ` Michael Haggerty
2011-09-30 16:38                                                               ` Junio C Hamano
2011-09-30 17:56                                                                 ` [PATCH] refs: Remove duplicates after sorting with qsort Julian Phillips
2011-10-02  5:15                                                                 ` [PATCH v3] refs: Use binary search to lookup refs faster Michael Haggerty
2011-10-02  5:45                                                                   ` Junio C Hamano
2011-10-04 20:58                                                                     ` Junio C Hamano
2011-09-30  1:13                                                           ` Martin Fick
2011-09-30  3:44                                                             ` Junio C Hamano
2011-09-30  8:04                                                               ` Julian Phillips
2011-09-30 15:45                                                               ` Martin Fick
2011-09-29 20:44                                                     ` Git is not scalable with too many refs/* Martin Fick
2011-09-29 19:10                                                   ` Julian Phillips
2011-09-29 20:11                                                   ` Martin Fick
2011-09-30  9:12                                                     ` René Scharfe
2011-09-30 16:09                                                       ` Martin Fick
2011-09-30 16:52                                                       ` Junio C Hamano
2011-09-30 18:17                                                         ` René Scharfe
2011-10-01 15:28                                                           ` René Scharfe
2011-10-01 15:38                                                             ` [PATCH 1/8] checkout: check for "Previous HEAD" notice in t2020 René Scharfe
2011-10-01 19:02                                                               ` Sverre Rabbelier
2011-10-01 15:43                                                             ` [PATCH 2/8] revision: factor out add_pending_sha1 René Scharfe
2011-10-01 15:51                                                             ` [PATCH 3/8] checkout: use add_pending_{object,sha1} in orphan check René Scharfe
2011-10-01 15:56                                                             ` [PATCH 4/8] revision: add leak_pending flag René Scharfe
2011-10-01 16:01                                                             ` [PATCH 5/8] bisect: use " René Scharfe
2011-10-01 16:02                                                             ` [PATCH 6/8] bundle: " René Scharfe
2011-10-01 16:09                                                             ` [PATCH 7/8] checkout: " René Scharfe
2011-10-01 16:16                                                             ` [PATCH 8/8] commit: factor out clear_commit_marks_for_object_array René Scharfe
2011-09-26 15:15                                     ` Martin Fick [this message]
2011-09-26 15:21                                       ` Git is not scalable with too many refs/* Sverre Rabbelier
2011-09-26 15:48                                         ` Martin Fick
2011-09-26 15:56                                           ` Sverre Rabbelier
2011-09-26 16:38                                             ` Martin Fick
2011-09-26 16:49                                               ` Julian Phillips
2011-09-26 18:07                                       ` Martin Fick
2011-09-26 18:37                                         ` Julian Phillips
2011-09-26 20:01                                           ` Martin Fick
2011-09-26 20:07                                             ` Junio C Hamano
2011-09-26 20:28                                             ` Julian Phillips
2011-09-26 21:39                                               ` Martin Fick
2011-09-26 21:52                                                 ` Martin Fick
2011-09-26 23:26                                                   ` Julian Phillips
2011-09-26 23:37                                                     ` David Michael Barr
2011-09-27  1:01                                                       ` [PATCH] refs.c: Fix slowness with numerous loose refs David Barr
2011-09-27  2:04                                                         ` David Michael Barr
2011-09-26 23:38                                                     ` Git is not scalable with too many refs/* Junio C Hamano
2011-09-27  0:00                                                       ` [PATCH] Don't sort ref_list too early Julian Phillips
2011-10-02  4:58                                                         ` Michael Haggerty
2011-09-27  0:12                                                     ` Git is not scalable with too many refs/* Martin Fick
2011-09-27  0:22                                                       ` Julian Phillips
2011-09-27  2:34                                                         ` Martin Fick
2011-09-27  7:59                                                           ` Julian Phillips
2011-09-27  8:20                                                     ` Sverre Rabbelier
2011-09-27  9:01                                                       ` Julian Phillips
2011-09-27 10:01                                                         ` Sverre Rabbelier
2011-09-27 10:25                                                           ` Nguyen Thai Ngoc Duy
2011-09-27 11:07                                                         ` Michael Haggerty
2011-09-27 12:10                                                           ` Julian Phillips
2011-09-26 22:30                                                 ` Julian Phillips
2011-09-26 15:32                                     ` Michael Haggerty
2011-09-26 15:42                                       ` Martin Fick
2011-09-26 16:25                                         ` Thomas Rast
2011-09-09 13:50                                 ` Michael Haggerty
2011-09-09 15:51                                   ` Michael Haggerty
2011-09-09 16:03                                   ` Jens Lehmann
2011-06-10  7:41         ` Andreas Ericsson
2011-06-10 19:41           ` Shawn Pearce
2011-06-10 20:12             ` Jakub Narebski
2011-06-10 20:35             ` Jeff King
2011-06-13  7:08             ` Andreas Ericsson
2011-06-09 11:18 ` Jakub Narebski
2011-06-09 15:42   ` Stephen Bash

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