> writeback: remove the internal 5% low bound on dirty_ratio > > The dirty_ratio was silently limited in global_dirty_limits() to >= 5%. This > is not a user expected behavior. And it's inconsistent with calc_period_shift(), > which uses the plain vm_dirty_ratio value. So let's rip the internal bound. > > At the same time, force a user visible low bound of 1% for the vm.dirty_ratio > interface. Applications trying to write 0 will be rejected with -EINVAL. This > will break user space applications if they > 1) try to write 0 to vm.dirty_ratio > 2) and check the return value > That is very weird combination, so the risk of breaking user space is low. I'm ok this one too. because I bet nobody use 0% dirty ratio on their production server and/or their own desktop. (i.e. I don't mind lab machine crash) Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> > > CC: Jan Kara <jack@xxxxxxx> > CC: Neil Brown <neilb@xxxxxxx> > CC: Rik van Riel <riel@xxxxxxxxxx> > CC: Con Kolivas <kernel@xxxxxxxxxxx> > CC: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> > CC: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> > Signed-off-by: Wu Fengguang <fengguang.wu@xxxxxxxxx> > --- > kernel/sysctl.c | 2 +- > mm/page-writeback.c | 10 ++-------- > 2 files changed, 3 insertions(+), 9 deletions(-) > > --- linux-next.orig/mm/page-writeback.c 2010-08-20 20:14:11.000000000 +0800 > +++ linux-next/mm/page-writeback.c 2010-08-23 10:31:01.000000000 +0800 > @@ -415,14 +415,8 @@ void global_dirty_limits(unsigned long * > > if (vm_dirty_bytes) > dirty = DIV_ROUND_UP(vm_dirty_bytes, PAGE_SIZE); > - else { > - int dirty_ratio; > - > - dirty_ratio = vm_dirty_ratio; > - if (dirty_ratio < 5) > - dirty_ratio = 5; > - dirty = (dirty_ratio * available_memory) / 100; > - } > + else > + dirty = (vm_dirty_ratio * available_memory) / 100; > > if (dirty_background_bytes) > background = DIV_ROUND_UP(dirty_background_bytes, PAGE_SIZE); > --- linux-next.orig/kernel/sysctl.c 2010-08-23 14:06:11.000000000 +0800 > +++ linux-next/kernel/sysctl.c 2010-08-23 14:07:30.000000000 +0800 > @@ -1029,7 +1029,7 @@ static struct ctl_table vm_table[] = { > .maxlen = sizeof(vm_dirty_ratio), > .mode = 0644, > .proc_handler = dirty_ratio_handler, > - .extra1 = &zero, > + .extra1 = &one, > .extra2 = &one_hundred, > }, > { -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html