Re: WALWriteLock contention

On May 17, 2015, at 5:57 PM, Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com> wrote:
>> On Sun, May 17, 2015 at 2:15 PM, Robert Haas <robertmhaas(at)gmail(dot)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