Re: Re[2]: Allowing WAL fsync to be done via O_SYNC

* Xu Yifeng <jamexu(at)telekbird(dot)com(dot)cn> [010315 22:25] wrote:
> Hello Tom,
>
> Friday, March 16, 2001, 6:54:22 AM, you wrote:
>
> TL> Alfred Perlstein <bright(at)wintelcom(dot)net> writes:
> >> How many files need to be fsync'd?
>
> TL> Only one.
>
> >> If it's more than one, what might work is using mmap() to map the
> >> files in adjacent areas, then calling msync() on the entire range,
> >> this would allow you to batch fsync the data.
>
> TL> Interesting thought, but mmap to a prespecified address is most
> TL> definitely not portable, whether or not you want to assume that
> TL> plain mmap is ...
>
> TL> regards, tom lane
>
> Could anyone consider fork a syncer process to sync data to disk ?
> build a shared sync queue, when a daemon process want to do sync after
> write() is called, just put a sync request to the queue. this can release
> process from blocked on writing as soon as possible. multipile sync
> request for one file can be merged when the request is been inserting to
> the queue.

I suggested this about a year ago. :)

The problem is that you need that process to potentially open and close
many files over and over.

I still think it's somewhat of a good idea.

--
-Alfred Perlstein - [bright(at)wintelcom(dot)net|alfred(at)freebsd(dot)org]