> > > > Ahh, now I see; I had totally blocked out these few lines:
> > > >
> > > > pages_written += write_chunk - wbc.nr_to_write;
> > > > if (pages_written >= write_chunk)
> > > > break; /* We've done our duty */
> > > >
> > > > yeah, those look dubious indeed... And reading back Neil's comments, I
> > > > think he agrees.
> > > >
> > > > Shall we just kill those?
> > >
> > > I think we should.
> > >
> > > Athough I'm a little afraid, that Akpm will tell me again, that I'm a
> > > stupid git, and that those lines are in fact vitally important ;)
> > >
> >
> > It depends what they're replaced with.
> >
> > That code is there, iirc, to prevent a process from getting stuck in
> > balance_dirty_pages() forever due to the dirtying activity of other
> > processes.
> >
> > hm, we ask the process to write write_chunk pages each go around the loop.
> > So if it wrote write-chunk/2 pages on the first pass it might end up writing
> > write_chunk*1.5 pages total. I guess that's rare and doesn't matter much
> > if it does happen - the upper bound is write_chunk*2-1, I think.
>
> Right, but I think the problem is that its dirty -> writeback, not dirty
> -> writeback completed.
>
> Ie. they don't guarantee progress, it could be that the total
> nr_reclaimable + nr_writeback will steadily increase due to this break.
>
> How about ensuring that vm_writeout_total increases least
> 2*sync_writeback_pages() during our stay in balance_dirty_pages(). That
> way we have the guarantee that more pages get written out than can be
> dirtied.
No, because that's a global counter, which many writers could be
looking at.
We'd need a per-task writeout counter, but when finishing the write we
don't know anymore which task it was performed for.
Miklos
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
