Re: [PATCH] loop: Add PF_LESS_THROTTLE to block/loop device thread.

2017-04-04 Thread Ming Lei
On Wed, Apr 5, 2017 at 12:27 PM, NeilBrown wrote: > On Tue, Apr 04 2017, Christoph Hellwig wrote: > >> Looks fine, >> >> Reviewed-by: Christoph Hellwig >> >> But if you actually care about performance in any way I'd suggest >> to use the loop device in direct I/O mode.. > > The losetup on my test

Re: [PATCH] loop: Add PF_LESS_THROTTLE to block/loop device thread.

2017-04-04 Thread NeilBrown
On Tue, Apr 04 2017, Ming Lei wrote: > On Mon, Apr 3, 2017 at 9:18 AM, NeilBrown wrote: >> >> When a filesystem is mounted from a loop device, writes are >> throttled by balance_dirty_pages() twice: once when writing >> to the filesystem and once when the loop_handle_cmd() writes >> to the backin

Re: [PATCH] loop: Add PF_LESS_THROTTLE to block/loop device thread.

2017-04-04 Thread NeilBrown
On Tue, Apr 04 2017, Christoph Hellwig wrote: > Looks fine, > > Reviewed-by: Christoph Hellwig > > But if you actually care about performance in any way I'd suggest > to use the loop device in direct I/O mode.. The losetup on my test VM is too old to support that :-( I guess it might be time to

Re: [PATCH] loop: Add PF_LESS_THROTTLE to block/loop device thread.

2017-04-04 Thread Ming Lei
On Mon, Apr 3, 2017 at 9:18 AM, NeilBrown wrote: > > When a filesystem is mounted from a loop device, writes are > throttled by balance_dirty_pages() twice: once when writing > to the filesystem and once when the loop_handle_cmd() writes > to the backing file. This double-throttling can trigger >

Re: [PATCH] loop: Add PF_LESS_THROTTLE to block/loop device thread.

2017-04-04 Thread Michal Hocko
On Mon 03-04-17 11:18:51, NeilBrown wrote: > > When a filesystem is mounted from a loop device, writes are > throttled by balance_dirty_pages() twice: once when writing > to the filesystem and once when the loop_handle_cmd() writes > to the backing file. This double-throttling can trigger > posit

Re: [PATCH] loop: Add PF_LESS_THROTTLE to block/loop device thread.

2017-04-04 Thread Christoph Hellwig
Looks fine, Reviewed-by: Christoph Hellwig But if you actually care about performance in any way I'd suggest to use the loop device in direct I/O mode..

[PATCH] loop: Add PF_LESS_THROTTLE to block/loop device thread.

2017-04-02 Thread NeilBrown
When a filesystem is mounted from a loop device, writes are throttled by balance_dirty_pages() twice: once when writing to the filesystem and once when the loop_handle_cmd() writes to the backing file. This double-throttling can trigger positive feedback loops that create significant delays. The