From: Junio C Hamano <gitster@pobox.com>
To: Stefan Beller <sbeller@google.com>
Cc: git@vger.kernel.org, peff@peff.net, torvalds@linux-foundation.org
Subject: Re: [PATCH] Enable core.fsyncObjectFiles by default
Date: Tue, 23 Jun 2015 15:21:44 -0700 [thread overview]
Message-ID: <xmqqpp4maww7.fsf@gitster.dls.corp.google.com> (raw)
In-Reply-To: <1435096643-18159-1-git-send-email-sbeller@google.com> (Stefan Beller's message of "Tue, 23 Jun 2015 14:57:23 -0700")
Stefan Beller <sbeller@google.com> writes:
> Linus Torvalds started a discussion[1] if we want to play rather safe
> than use defaults which make sense only for the most power users of Git:
>
>> So git is "safe" in the sense that you won't really lose any data,
>> but you may well be inconvenienced. The "fsync each object" config
>> option is there in case you don't want that inconvenience, but it
>> should be noted that it can make for a hell of a performance impact.
>
>> Of course, it might well be the case that the actual default
>> might be worth turning around. Most git users probably don't
>> care about that kind of "apply two hundred patches from Andrew
>> Morton" kind of workload, although "rebase a big patch-series"
>> does end up doing basically the same thing, and might be more
>> common.
>
> This patch enables fsync_object_files by default.
Sorry, but I fail to see which part of what Linus said (which is the
only thing you quoted from the discussion) argues for this patch.
If anything, I read that as cautioning people against making a
tradeoff based on an incorrect perception of risks and blindly
flipping this bit ON (the original discussion a few days ago, where
Ted says he has this bit ON while clarifying that he does so on SSD,
is also a sensible description on how he made his trade-off).
It's a different matter whom you would want to align with when
assessing your own risk tolerance. If you quoted Corbet's original
message, then that would have been more consistent.
>
> [1] https://plus.google.com/u/1/+JonathanCorbet/posts/JBxiKPe3VXa
>
> Signed-off-by: Stefan Beller <sbeller@google.com>
> ---
> Documentation/config.txt | 8 ++++----
> environment.c | 2 +-
> 2 files changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/Documentation/config.txt b/Documentation/config.txt
> index 43bb53c..dce2640 100644
> --- a/Documentation/config.txt
> +++ b/Documentation/config.txt
> @@ -693,10 +693,10 @@ core.whitespace::
> core.fsyncObjectFiles::
> This boolean will enable 'fsync()' when writing object files.
> +
> -This is a total waste of time and effort on a filesystem that orders
> -data writes properly, but can be useful for filesystems that do not use
> -journalling (traditional UNIX filesystems) or that only journal metadata
> -and not file contents (OS X's HFS+, or Linux ext3 with "data=writeback").
> +This ensures objects are written to disk instead of relying on the
> +operating systems cache and eventual write. Disabling this option will
> +yield performance with a trade off in safety for repository corruption
> +during power loss.
>
> core.preloadIndex::
> Enable parallel index preload for operations like 'git diff'
> diff --git a/environment.c b/environment.c
> index 61c685b..b406f5e 100644
> --- a/environment.c
> +++ b/environment.c
> @@ -35,7 +35,7 @@ const char *git_attributes_file;
> int zlib_compression_level = Z_BEST_SPEED;
> int core_compression_level;
> int core_compression_seen;
> -int fsync_object_files;
> +int fsync_object_files = 1;
> size_t packed_git_window_size = DEFAULT_PACKED_GIT_WINDOW_SIZE;
> size_t packed_git_limit = DEFAULT_PACKED_GIT_LIMIT;
> size_t delta_base_cache_limit = 96 * 1024 * 1024;
next prev parent reply other threads:[~2015-06-23 22:23 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-23 21:57 [PATCH] Enable core.fsyncObjectFiles by default Stefan Beller
2015-06-23 22:21 ` Junio C Hamano [this message]
2015-06-23 23:29 ` Theodore Ts'o
2015-06-24 5:32 ` Junio C Hamano
2015-06-24 14:30 ` Theodore Ts'o
2015-06-24 1:07 ` Duy Nguyen
2015-06-24 3:37 ` Jeff King
2015-06-24 5:20 ` Junio C Hamano
2018-01-17 18:48 [PATCH] enable " Christoph Hellwig
2018-01-17 19:04 ` Junio C Hamano
2018-01-17 19:35 ` Christoph Hellwig
2018-01-17 20:05 ` Andreas Schwab
2018-01-17 19:37 ` Matthew Wilcox
2018-01-17 19:42 ` Christoph Hellwig
2018-01-17 21:44 ` Ævar Arnfjörð Bjarmason
2018-01-17 22:07 ` Linus Torvalds
2018-01-17 22:25 ` Linus Torvalds
2018-01-17 23:16 ` Ævar Arnfjörð Bjarmason
2018-01-17 23:42 ` Linus Torvalds
2018-01-17 23:52 ` Theodore Ts'o
2018-01-17 23:57 ` Linus Torvalds
2018-01-18 16:27 ` Christoph Hellwig
2018-01-19 19:08 ` Junio C Hamano
2018-01-20 22:14 ` Theodore Ts'o
2018-01-20 22:27 ` Junio C Hamano
2018-01-22 15:09 ` Ævar Arnfjörð Bjarmason
2018-01-22 18:09 ` Theodore Ts'o
2018-01-23 0:47 ` Jeff King
2018-01-23 5:45 ` Theodore Ts'o
2018-01-23 16:17 ` Jeff King
2018-01-23 0:25 ` Jeff King
2018-01-21 21:32 ` Chris Mason
2020-09-17 11:06 ` Ævar Arnfjörð Bjarmason
2020-09-17 14:14 ` Christoph Hellwig
2020-09-17 15:30 ` Junio C Hamano
2018-01-17 20:55 ` Jeff King
2018-01-17 21:10 ` Christoph Hellwig
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