Re: [PATCH] mm: add resched points to remap_pmd_range/ioremap_pmd_range

2015-08-06 Thread Mike Galbraith
On Thu, 2015-07-30 at 09:58 -0700, Jörn Engel wrote: > On Thu, Jul 30, 2015 at 05:22:55PM +0200, Mike Galbraith wrote: > > > > I piddled about with the thought that it might be nice to be able to > > sprinkle cond_resched() about to cut rt latencies without wrecking > > normal load throughput, cob

Re: [PATCH] mm: add resched points to remap_pmd_range/ioremap_pmd_range

2015-07-30 Thread Mike Galbraith
On Thu, 2015-07-30 at 09:58 -0700, Jörn Engel wrote: > On Thu, Jul 30, 2015 at 05:22:55PM +0200, Mike Galbraith wrote: > > > > I piddled about with the thought that it might be nice to be able to > > sprinkle cond_resched() about to cut rt latencies without wrecking > > normal load throughput, cob

Re: [PATCH] mm: add resched points to remap_pmd_range/ioremap_pmd_range

2015-07-30 Thread Jörn Engel
On Thu, Jul 30, 2015 at 05:22:55PM +0200, Mike Galbraith wrote: > > I piddled about with the thought that it might be nice to be able to > sprinkle cond_resched() about to cut rt latencies without wrecking > normal load throughput, cobbled together a cond_resched_rt(). > > On my little box that w

Re: [PATCH] mm: add resched points to remap_pmd_range/ioremap_pmd_range

2015-07-30 Thread Mike Galbraith
On Wed, 2015-07-29 at 11:54 +0200, Michal Hocko wrote: > On Tue 28-07-15 10:08:44, Jörn Engel wrote: > > On Tue, Jul 28, 2015 at 03:32:55PM +0200, Michal Hocko wrote: > > > > > > > > We have kernel preemption disabled. A lower-priority task in a system > > > > call will block higher-priority task

Re: [PATCH] mm: add resched points to remap_pmd_range/ioremap_pmd_range

2015-07-29 Thread Michal Hocko
On Tue 28-07-15 10:08:44, Jörn Engel wrote: > On Tue, Jul 28, 2015 at 03:32:55PM +0200, Michal Hocko wrote: > > > > > > We have kernel preemption disabled. A lower-priority task in a system > > > call will block higher-priority tasks. > > > > This is an inherent problem of !PREEMPT, though. Ther

Re: [PATCH] mm: add resched points to remap_pmd_range/ioremap_pmd_range

2015-07-28 Thread Jörn Engel
On Tue, Jul 28, 2015 at 03:32:55PM +0200, Michal Hocko wrote: > > > > We have kernel preemption disabled. A lower-priority task in a system > > call will block higher-priority tasks. > > This is an inherent problem of !PREEMPT, though. There are many > loops which can take quite some time but we

Re: [PATCH] mm: add resched points to remap_pmd_range/ioremap_pmd_range

2015-07-28 Thread Michal Hocko
On Mon 27-07-15 08:18:14, Jörn Engel wrote: > On Mon, Jul 27, 2015 at 09:08:42AM +0200, Michal Hocko wrote: > > On Fri 24-07-15 09:56:27, Jörn Engel wrote: > > > On Fri, Jul 24, 2015 at 09:04:21AM +0200, Michal Hocko wrote: > > > > On Thu 23-07-15 14:54:33, Spencer Baugh wrote: > > > > > From: Joer

Re: [PATCH] mm: add resched points to remap_pmd_range/ioremap_pmd_range

2015-07-27 Thread Jörn Engel
On Mon, Jul 27, 2015 at 09:08:42AM +0200, Michal Hocko wrote: > On Fri 24-07-15 09:56:27, Jörn Engel wrote: > > On Fri, Jul 24, 2015 at 09:04:21AM +0200, Michal Hocko wrote: > > > On Thu 23-07-15 14:54:33, Spencer Baugh wrote: > > > > From: Joern Engel > > > > > > > > Mapping large memory spaces

Re: [PATCH] mm: add resched points to remap_pmd_range/ioremap_pmd_range

2015-07-27 Thread Mike Galbraith
On Mon, 2015-07-27 at 09:08 +0200, Michal Hocko wrote: > On Fri 24-07-15 09:56:27, Jörn Engel wrote: > > On Fri, Jul 24, 2015 at 09:04:21AM +0200, Michal Hocko wrote: > > > On Thu 23-07-15 14:54:33, Spencer Baugh wrote: > > > > From: Joern Engel > > > > > > > > Mapping large memory spaces can be

Re: [PATCH] mm: add resched points to remap_pmd_range/ioremap_pmd_range

2015-07-27 Thread Michal Hocko
On Fri 24-07-15 09:56:27, Jörn Engel wrote: > On Fri, Jul 24, 2015 at 09:04:21AM +0200, Michal Hocko wrote: > > On Thu 23-07-15 14:54:33, Spencer Baugh wrote: > > > From: Joern Engel > > > > > > Mapping large memory spaces can be slow and prevent high-priority > > > realtime threads from preempti

Re: [PATCH] mm: add resched points to remap_pmd_range/ioremap_pmd_range

2015-07-24 Thread Jörn Engel
On Thu, Jul 23, 2015 at 05:32:03PM -0600, Toshi Kani wrote: > On Thu, 2015-07-23 at 14:54 -0700, Spencer Baugh wrote: > > From: Joern Engel > > > > Mapping large memory spaces can be slow and prevent high-priority > > realtime threads from preempting lower-priority threads for a long time. > > Y

Re: [PATCH] mm: add resched points to remap_pmd_range/ioremap_pmd_range

2015-07-24 Thread Jörn Engel
On Fri, Jul 24, 2015 at 09:04:21AM +0200, Michal Hocko wrote: > On Thu 23-07-15 14:54:33, Spencer Baugh wrote: > > From: Joern Engel > > > > Mapping large memory spaces can be slow and prevent high-priority > > realtime threads from preempting lower-priority threads for a long time. > > How can

Re: [PATCH] mm: add resched points to remap_pmd_range/ioremap_pmd_range

2015-07-24 Thread Michal Hocko
On Thu 23-07-15 14:54:33, Spencer Baugh wrote: > From: Joern Engel > > Mapping large memory spaces can be slow and prevent high-priority > realtime threads from preempting lower-priority threads for a long time. How can a lower priority task block the high priority one? Do you have preemption di

Re: [PATCH] mm: add resched points to remap_pmd_range/ioremap_pmd_range

2015-07-23 Thread Toshi Kani
On Thu, 2015-07-23 at 14:54 -0700, Spencer Baugh wrote: > From: Joern Engel > > Mapping large memory spaces can be slow and prevent high-priority > realtime threads from preempting lower-priority threads for a long time. Yes, and one of the goals of large page ioremap support is to address such

[PATCH] mm: add resched points to remap_pmd_range/ioremap_pmd_range

2015-07-23 Thread Spencer Baugh
From: Joern Engel Mapping large memory spaces can be slow and prevent high-priority realtime threads from preempting lower-priority threads for a long time. In my case it was a 256GB mapping causing at least 950ms scheduler delay. Problem detection is ratelimited and depends on interrupts happen