On Thu, Jun 07, 2012 at 11:23:45AM +1000, NeilBrown wrote: > On Mon, 04 Jun 2012 16:01:58 +0800 Shaohua Li <shli@xxxxxxxxxx> wrote: > > > make_request() does stripe release for every stripe and the stripe usually has > > count 1, which makes previous release_stripe() optimization not work. In my > > test, this release_stripe() becomes the heaviest pleace to take > > conf->device_lock after previous patches applied. > > > > Below patch makes stripe release batch. When maxium strips of a batch reach, > > the batch will be flushed out. Another way to do the flush is when unplug is > > called. > > > > Signed-off-by: Shaohua Li <shli@xxxxxxxxxxxx> > > I like the idea of a batched release. > I don't like the per-cpu variables... and I don't think it is safe to only > allocate them for_each_present_cpu without support cpu-hot-plug. > > I would much rather keep a list of stripes (linked on ->lru) in struct > md_plug_cb (or maybe in some structure which contains that) and release them > all on unplug - and only on unplug. > > Maybe pass a size to mddev_check_unplugged, and it allocates that much more > space. Get mddev_check_unplugged to return the md_plug_cb structure. > If the new space is NULL, then list_head_init it, and change the cb.callback > to a raid5 specific function. > Then add any stripe to the md_plug_cb, and in the unplug function, release > them all. > > Does that make sense? > > Also I would rather the batched stripe release code were defined in the same > patch that used it. It isn't big enough to justify a separate patch. The stripe->lru need protection of device_lock, so I can't use a list. An array is preferred. I really didn't like the idea to allocate memory especially when allocating an array. I'll fix the code for cpuhotplug. -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
