Re: User mode stalls - can it be...?

[Roger Larsson <roger.larsson@norran.net>]

"Stephen C. Tweedie" wrote:
> 
> Hi,
> 
> On Wed, Jul 05, 2000 at 03:29:22AM +0200, Roger Larsson wrote:
> >
> > static void sync_page_buffers(struct buffer_head *bh, int wait)
> > {
> >       struct buffer_head * tmp = bh;
> >
> >       do {
> >               struct buffer_head *p = tmp;
> >               tmp = tmp->b_this_page;
> >               if (!buffer_locked(p) &&
> >                     buffer_dirty(p))
> >                       ll_rw_block(WRITE, 1, &p);
> >               if (wait)
> >                       __wait_on_buffer(p);
> >       } while (tmp != bh);
> 
> Yikes no.  That will make the syncer wait for every single write
> synchronously.  It will cause a page full of 1k buffers to be written
> out as four separate 1k writes instead of being streamed.  This will
> _kill_ performance.
> 
> Cheers,
>  Stephen


Well, 'wait' is not set at each call...

But I agree that it was not a wery bright idea...
(I am more awake now :-)

/RogerL

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