From: Neeraj Singh <nksingh85@gmail.com>
To: Junio C Hamano <gitster@pobox.com>
Cc: Chris Torek <chris.torek@gmail.com>,
Jeff Hostetler <git@jeffhostetler.com>,
Git List <git@vger.kernel.org>,
"Neeraj K. Singh" <neerajsi@microsoft.com>
Subject: Re: [PATCH] read-cache: make the index write buffer size 128K
Date: Wed, 24 Feb 2021 23:36:20 -0800 [thread overview]
Message-ID: <CANQDOdd+keN3LyC4CHWDZ3JHYurEy_FLyw5GT5UKqg0RcTA+DA@mail.gmail.com> (raw)
In-Reply-To: <xmqqeeh4wrad.fsf@gitster.g>
On Wed, Feb 24, 2021 at 11:16 PM Junio C Hamano <gitster@pobox.com> wrote:
>
> Chris Torek <chris.torek@gmail.com> writes:
>
> > Linux/BSD/etc `stat` system calls report st_blksize values to tell
> > user code the optimal size for read and write calls. Does Windows
> > have one? (It's not POSIX but is XSI.)
> >
> > (How *well* the OS reports `st_blksize` is another question
> > entirely, but at least if the report says, say, 128k, and that's
> > wrong, that's no longer Git's fault. :-) )
> > ...
> > 128K is correct for ZFS; 64K is typically correct for UFS2; 8K is
> > the old UFS1 size. Anything under that has been too small for
> > a long time. :-)
>
> That's rather tempting. After opening a locked index to write
> things out, the value is a single fstat() away...
>
From a quick perusal of freebsd, st_blksize seems to be the system
PAGE_SIZE by default (4k most of the time, I assume). The Windows
equivalent of this value is really tuned to what you want to send down
when bypassing the cache (to avoid partial cluster/stripe writes).
https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/sys_stat.h.html
doesn't elicit much confidence. The units of st_blksize aren't even
defined.
Thanks,
Neeraj
next prev parent reply other threads:[~2021-02-25 7:47 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-18 2:48 [PATCH] read-cache: make the index write buffer size 128K Neeraj K. Singh via GitGitGadget
2021-02-19 19:12 ` Jeff Hostetler
2021-02-20 3:28 ` Junio C Hamano
2021-02-20 7:56 ` Neeraj Singh
2021-02-21 12:51 ` Junio C Hamano
2021-02-24 20:56 ` Neeraj Singh
2021-02-25 5:41 ` Junio C Hamano
2021-02-25 6:58 ` Chris Torek
2021-02-25 7:16 ` Junio C Hamano
2021-02-25 7:36 ` Neeraj Singh [this message]
2021-02-25 7:57 ` Chris Torek
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
List information: http://vger.kernel.org/majordomo-info.html
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CANQDOdd+keN3LyC4CHWDZ3JHYurEy_FLyw5GT5UKqg0RcTA+DA@mail.gmail.com \
--to=nksingh85@gmail.com \
--cc=chris.torek@gmail.com \
--cc=git@jeffhostetler.com \
--cc=git@vger.kernel.org \
--cc=gitster@pobox.com \
--cc=neerajsi@microsoft.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this public inbox
https://80x24.org/mirrors/git.git
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).