Re: [RFC][PATCH 0/3] VM throttling: avoid blocking occasionalwriters

[KAMEZAWA Hiroyuki]

On Tue, 27 Feb 2007 09:50:16 +0900
Tomoki Sekiyama <tomoki.sekiyama.qu@xxxxxxxxxxx> wrote:

> Hi Kamezawa-san,
> 
> thanks for your reply.
> 
> KAMEZAWA Hiroyuki wrote:
> > Interesting, but how about adjust this parameter like below instead of
> > adding new control knob ?(this kind of knob is not easy to use.)
> >
> > ==
> >                 struct writeback_control wbc = {
> >                         .bdi            = bdi,
> >                         .sync_mode      = WB_SYNC_NONE,
> >                         .older_than_this = NULL,
> >                         .nr_to_write    = 0,
> >                         .range_cyclic   = 1,
> >                 };
> > <snip>
> >                 if (nr_reclaimable) {
> > 			/* Just do what I can do */
> > 			dirty_pages_on_device = count_dirty_pages_on_device_limited(bdi, writechunk);
> > 			wbc.nr_to_write = dirty_pages_on_device.
> > 			writeback_inodes(&wbc);
> >
> > ==
> >
> > count_dirty_pages_on_device_limited(bdi, writechunk) above returns
> > dirty pages on bdi. if # of dirty_pages on bdi is larger than writechunk,
> > just returns writechunk.
> 
> 
> I think that way is not enough to control the total amount of
> Dirty+Writeback.
> 
> In that way, while writeback_inodes() scans for dirty pages and writes
> them back, the caller will be blocked only if the length of the write-
> requests queue is longer than nr_requests.
What nr_request means ?
But Ok, maybe I'm not understanding. What I want to ask you is do 
per-device-write-throttling rather than adding a new parameter.

Bye.
-Kame



-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/