Re: [PATCH v2] loop: Add PF_LESS_THROTTLE to block/loop device thread.

2017-04-06 Thread Michal Hocko
On Thu 06-04-17 12:23:51, NeilBrown wrote: [...] > diff --git a/drivers/block/loop.c b/drivers/block/loop.c > index 0ecb6461ed81..95679d988725 100644 > --- a/drivers/block/loop.c > +++ b/drivers/block/loop.c > @@ -847,10 +847,12 @@ static void loop_unprepare_queue(struct loop_device *lo) > static

Re: [PATCH v2] loop: Add PF_LESS_THROTTLE to block/loop device thread.

2017-04-06 Thread Michal Hocko
On Thu 06-04-17 12:23:51, NeilBrown wrote: [...] > diff --git a/drivers/block/loop.c b/drivers/block/loop.c > index 0ecb6461ed81..95679d988725 100644 > --- a/drivers/block/loop.c > +++ b/drivers/block/loop.c > @@ -847,10 +847,12 @@ static void loop_unprepare_queue(struct loop_device *lo) > static

Re: [PATCH v2] loop: Add PF_LESS_THROTTLE to block/loop device thread.

2017-04-05 Thread NeilBrown
On Wed, Apr 05 2017, Michal Hocko wrote: > On Wed 05-04-17 09:19:27, Michal Hocko wrote: >> On Wed 05-04-17 14:33:50, NeilBrown wrote: > [...] >> > diff --git a/drivers/block/loop.c b/drivers/block/loop.c >> > index 0ecb6461ed81..44b3506fd086 100644 >> > --- a/drivers/block/loop.c >> > +++

Re: [PATCH v2] loop: Add PF_LESS_THROTTLE to block/loop device thread.

2017-04-05 Thread NeilBrown
On Wed, Apr 05 2017, Michal Hocko wrote: > On Wed 05-04-17 09:19:27, Michal Hocko wrote: >> On Wed 05-04-17 14:33:50, NeilBrown wrote: > [...] >> > diff --git a/drivers/block/loop.c b/drivers/block/loop.c >> > index 0ecb6461ed81..44b3506fd086 100644 >> > --- a/drivers/block/loop.c >> > +++

Re: [PATCH v2] loop: Add PF_LESS_THROTTLE to block/loop device thread.

2017-04-05 Thread Michal Hocko
On Wed 05-04-17 09:19:27, Michal Hocko wrote: > On Wed 05-04-17 14:33:50, NeilBrown wrote: [...] > > diff --git a/drivers/block/loop.c b/drivers/block/loop.c > > index 0ecb6461ed81..44b3506fd086 100644 > > --- a/drivers/block/loop.c > > +++ b/drivers/block/loop.c > > @@ -852,6 +852,7 @@ static int

Re: [PATCH v2] loop: Add PF_LESS_THROTTLE to block/loop device thread.

2017-04-05 Thread Michal Hocko
On Wed 05-04-17 09:19:27, Michal Hocko wrote: > On Wed 05-04-17 14:33:50, NeilBrown wrote: [...] > > diff --git a/drivers/block/loop.c b/drivers/block/loop.c > > index 0ecb6461ed81..44b3506fd086 100644 > > --- a/drivers/block/loop.c > > +++ b/drivers/block/loop.c > > @@ -852,6 +852,7 @@ static int

Re: [PATCH v2] loop: Add PF_LESS_THROTTLE to block/loop device thread.

2017-04-05 Thread Michal Hocko
On Wed 05-04-17 14:33:50, 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 v2] loop: Add PF_LESS_THROTTLE to block/loop device thread.

2017-04-05 Thread Michal Hocko
On Wed 05-04-17 14:33:50, 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 v2] loop: Add PF_LESS_THROTTLE to block/loop device thread.

2017-04-04 Thread Ming Lei
On Wed, Apr 5, 2017 at 12:33 PM, 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

Re: [PATCH v2] loop: Add PF_LESS_THROTTLE to block/loop device thread.

2017-04-04 Thread Ming Lei
On Wed, Apr 5, 2017 at 12:33 PM, 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

[PATCH v2] loop: Add PF_LESS_THROTTLE to block/loop device thread.

2017-04-04 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.

[PATCH v2] loop: Add PF_LESS_THROTTLE to block/loop device thread.

2017-04-04 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.