Re: [PATCH 3/8] writeback: switch to per-bdi threads for flushingdata v2

From: Jens Axboe
Date: Mon Sep 07 2009 - 15:50:52 EST

On Mon, Sep 07 2009, Jan Kara wrote:
> On Mon 07-09-09 20:45:18, Jens Axboe wrote:
> > On Mon, Sep 07 2009, Jan Kara wrote:
> > > Hi Jens,
> > >
> > > now I've found just two minor things (see below). Besides them the only
> > > thing which is blocking my ack is a way to effectively lookup a BDI from a
> > > superblock so that we can reasonably effectively fsync a superblock...
> >
> > Can we side step that as an inclusion criteria, please? I'd really like
> > to work on adding that quick lookup, but I'd also hate to potentiall
> > destabilize anything at this point. So we can probably quite easily make
> > .32 as well for that, but I'd rather not risk doing a version and
> > include that from the beginning. OK?
> Well, for now I thought about a simple hack like a pointer to
> backing_dev_info in a superblock. That should work for every filesystem
> right now and shouldn't be too complex...

Oh certainly, it wont be complex. But there's still a risk with
operations such as that, referencing to something new...

> But if you promise you'll fix that up before 2.6.32 is released, I'm OK
> with your patch as is. I'll give your patches some testing with some less
> usual benchmarks this week and if that works out fine you have my ack.

I promise :-)

Let me post a new version tomorrow, and you can base your tests off

Jens Axboe

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