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Re: [PATCH] read-cache: make the index write buffer size 128K

From
Chris Torek <chris.torek@gmail.com>
Date
Feb 25, 2021, 07:57 UTC
Message-ID
<CAPx1GvcFMzrFFmwMvDLofj73UcEi6T3u_v+usvENkU2yYGLoaQ@mail.gmail.com>
In-Reply-To
<CANQDOdd+keN3LyC4CHWDZ3JHYurEy_FLyw5GT5UKqg0RcTA+DA@mail.gmail.com>
On Wed, Feb 24, 2021 at 11:36 PM Neeraj Singh <nksingh85@gmail.com> wrote:
> 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).

It's page-size for pipes, sockets, etc., but for real files, it's based on a report from the underlying file system. It's actually 8k on a typical ancient UFS file system, 64K on UFS2, and 128K on ZFS, on FreeBSD.

> 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.

Despite POSIX's rather obstreperous definition of st_blksize, the units are actually just bytes, in practice.

Chris
Previous: Neeraj Singh
Message 11 of 11 in “read-cache: make the index write buffer size 128K”
  1. read-cache: make the index write buffer size 128KNeeraj K. Singh via GitGitGadget, Feb 18, 2021
  2. Jeff HostetlerFeb 19, 2021
  3. Junio C HamanoFeb 20, 2021
  4. Neeraj SinghFeb 20, 2021
  5. Junio C HamanoFeb 21, 2021
  6. Neeraj SinghFeb 24, 2021
  7. Junio C HamanoFeb 25, 2021
  8. Chris TorekFeb 25, 2021
  9. Junio C HamanoFeb 25, 2021
  10. Neeraj SinghFeb 25, 2021
  11. Chris TorekFeb 25, 2021

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