Re: Bgwriter behavior - Mailing list pgsql-hackers

From Bruce Momjian
Subject Re: Bgwriter behavior
Date
Msg-id 200412231616.iBNGGIG08618@candle.pha.pa.us
Whole thread Raw
In response to Re: Bgwriter behavior  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
Tom Lane wrote:
> Bruce Momjian <pgman@candle.pha.pa.us> writes:
> > I remember the other difference between 8.0 and pre-8.0.  When a backend
> > has to write a block in 8.0, it does a write _plus_ fsync(), while in
> > pre-8.0 it did only a write.  There was a proposal to pass backend write
> > information to the background writer so it would know to fsync at
> > checkpoint, but it was decided that backend writing would be rare.  I
> > think we have to rethink that assumption.
> 
> No, just read the code.  The above assertions are all wet.

Oh, I forgot you added that array to pass fsync info.

Shouldn't we send a log message when the array gets full in md.c:
   {       if (ForwardFsyncRequest(reln->smgr_rnode, seg->mdfd_segno))           return true;   }
   if (FileSync(seg->mdfd_vfd) < 0)       return false;

Seems that could fill up quickly.  I see no checking for existing
matching records in the array.

--  Bruce Momjian                        |  http://candle.pha.pa.us pgman@candle.pha.pa.us               |  (610)
359-1001+  If your life is a hard drive,     |  13 Roberts Road +  Christ can be your backup.        |  Newtown Square,
Pennsylvania19073
 


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