Re: WALWriteLock contention - Mailing list pgsql-hackers

From Robert Haas
Subject Re: WALWriteLock contention
Date
Msg-id 1A2EB8B9-A05F-4F09-AC41-70D4B62A0F55@gmail.com
Whole thread Raw
In response to Re: WALWriteLock contention  (Thomas Munro <thomas.munro@enterprisedb.com>)
List pgsql-hackers
On May 17, 2015, at 5:57 PM, Thomas Munro <thomas.munro@enterprisedb.com> wrote:
>> On Sun, May 17, 2015 at 2:15 PM, Robert Haas <robertmhaas@gmail.com> wrote:
>> http://oldblog.antirez.com/post/fsync-different-thread-useless.html
>>
>> It suggests that an fsync in progress blocks out not only other
>> fsyncs, but other writes to the same file, which for our purposes is
>> just awful.  More Googling around reveals that this is apparently
>> well-known to Linux kernel developers and that they don't seem excited
>> about fixing it.  :-(
>
> He doesn't say, but I wonder if that is really Linux, or if it is the
> ext2, 3 and maybe 4 filesystems specifically.  This blog post talks
> about the per-inode mutex that is held while writing with direct IO.

Good point. We should probably test ext4 and xfs on a newish kernel.

...Robert


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