Re: [PATCH 0/2] Disable zone_reclaim_mode by default v2

2014-04-20 Thread Mel Gorman
On Fri, Apr 18, 2014 at 04:48:25PM -0400, John Stoffel wrote: > > "Andrew" == Andrew Morton writes: > > Andrew> On Tue, 8 Apr 2014 09:22:58 +0100 Mel Gorman wrote: > >> Changelog since v1 > >> o topology comment updates > >> > >> When it was introduced, zone_reclaim_mode made sense as

Re: [PATCH 0/2] Disable zone_reclaim_mode by default v2

2014-04-20 Thread Mel Gorman
On Fri, Apr 18, 2014 at 04:48:25PM -0400, John Stoffel wrote: Andrew == Andrew Morton a...@linux-foundation.org writes: Andrew On Tue, 8 Apr 2014 09:22:58 +0100 Mel Gorman mgor...@suse.de wrote: Changelog since v1 o topology comment updates When it was introduced, zone_reclaim_mode

Re: [PATCH 0/2] Disable zone_reclaim_mode by default v2

2014-04-18 Thread John Stoffel
> "Andrew" == Andrew Morton writes: Andrew> On Tue, 8 Apr 2014 09:22:58 +0100 Mel Gorman wrote: >> Changelog since v1 >> o topology comment updates >> >> When it was introduced, zone_reclaim_mode made sense as NUMA distances >> punished and workloads were generally partitioned to fit into

Re: [PATCH 0/2] Disable zone_reclaim_mode by default v2

2014-04-18 Thread Andrew Morton
On Tue, 8 Apr 2014 09:22:58 +0100 Mel Gorman wrote: > Changelog since v1 > o topology comment updates > > When it was introduced, zone_reclaim_mode made sense as NUMA distances > punished and workloads were generally partitioned to fit into a NUMA > node. NUMA machines are now common but few

Re: [PATCH 0/2] Disable zone_reclaim_mode by default

2014-04-18 Thread Christoph Lameter
On Fri, 18 Apr 2014, Michal Hocko wrote: > Auto-enabling caused so many reports in the past that it is definitely > much better to not be clever and let admins enable zone_reclaim where it > is appropriate instead. > > For both patches. > Acked-by: Michal Hocko I did not get any objections from

Re: [PATCH 0/2] Disable zone_reclaim_mode by default

2014-04-18 Thread Michal Hocko
On Mon 07-04-14 23:34:26, Mel Gorman wrote: > When it was introduced, zone_reclaim_mode made sense as NUMA distances > punished and workloads were generally partitioned to fit into a NUMA > node. NUMA machines are now common but few of the workloads are NUMA-aware > and it's routine to see major

Re: [PATCH 0/2] Disable zone_reclaim_mode by default

2014-04-18 Thread Michal Hocko
On Mon 07-04-14 23:34:26, Mel Gorman wrote: When it was introduced, zone_reclaim_mode made sense as NUMA distances punished and workloads were generally partitioned to fit into a NUMA node. NUMA machines are now common but few of the workloads are NUMA-aware and it's routine to see major

Re: [PATCH 0/2] Disable zone_reclaim_mode by default

2014-04-18 Thread Christoph Lameter
On Fri, 18 Apr 2014, Michal Hocko wrote: Auto-enabling caused so many reports in the past that it is definitely much better to not be clever and let admins enable zone_reclaim where it is appropriate instead. For both patches. Acked-by: Michal Hocko mho...@suse.cz I did not get any

Re: [PATCH 0/2] Disable zone_reclaim_mode by default v2

2014-04-18 Thread Andrew Morton
On Tue, 8 Apr 2014 09:22:58 +0100 Mel Gorman mgor...@suse.de wrote: Changelog since v1 o topology comment updates When it was introduced, zone_reclaim_mode made sense as NUMA distances punished and workloads were generally partitioned to fit into a NUMA node. NUMA machines are now common

Re: [PATCH 0/2] Disable zone_reclaim_mode by default v2

2014-04-18 Thread John Stoffel
Andrew == Andrew Morton a...@linux-foundation.org writes: Andrew On Tue, 8 Apr 2014 09:22:58 +0100 Mel Gorman mgor...@suse.de wrote: Changelog since v1 o topology comment updates When it was introduced, zone_reclaim_mode made sense as NUMA distances punished and workloads were generally

Re: [PATCH 0/2] Disable zone_reclaim_mode by default

2014-04-10 Thread Jeremy Harris
On 08/04/14 23:58, Christoph Lameter wrote: The reason that zone reclaim is on by default is that off node accesses are a big performance hit on large scale NUMA systems (like ScaleMP and SGI). Zone reclaim was written *because* those system experienced severe performance degradation. On the

Re: [PATCH 0/2] Disable zone_reclaim_mode by default

2014-04-10 Thread Jeremy Harris
On 08/04/14 23:58, Christoph Lameter wrote: The reason that zone reclaim is on by default is that off node accesses are a big performance hit on large scale NUMA systems (like ScaleMP and SGI). Zone reclaim was written *because* those system experienced severe performance degradation. On the

Re: [PATCH 0/2] Disable zone_reclaim_mode by default

2014-04-09 Thread Mel Gorman
On Tue, Apr 08, 2014 at 03:56:49PM -0400, Josh Berkus wrote: > On 04/08/2014 03:53 PM, Robert Haas wrote: > > In an ideal world, the kernel would put the hottest pages on the local > > node and the less-hot pages on remote nodes, moving pages around as > > the workload shifts. In practice, that's

Re: [PATCH 0/2] Disable zone_reclaim_mode by default

2014-04-09 Thread Mel Gorman
On Tue, Apr 08, 2014 at 03:56:49PM -0400, Josh Berkus wrote: On 04/08/2014 03:53 PM, Robert Haas wrote: In an ideal world, the kernel would put the hottest pages on the local node and the less-hot pages on remote nodes, moving pages around as the workload shifts. In practice, that's

Re: [PATCH 0/2] Disable zone_reclaim_mode by default

2014-04-08 Thread Mel Gorman
On Tue, Apr 08, 2014 at 05:58:21PM -0500, Christoph Lameter wrote: > On Tue, 8 Apr 2014, Robert Haas wrote: > > > Well, as Josh quite rightly said, the hit from accessing remote memory > > is never going to be as large as the hit from disk. If and when there > > is a machine where remote memory

Re: [PATCH 0/2] Disable zone_reclaim_mode by default

2014-04-08 Thread Christoph Lameter
On Tue, 8 Apr 2014, Robert Haas wrote: > Well, as Josh quite rightly said, the hit from accessing remote memory > is never going to be as large as the hit from disk. If and when there > is a machine where remote memory is more expensive to access than > disk, that's a good argument for

Re: [PATCH 0/2] Disable zone_reclaim_mode by default

2014-04-08 Thread Josh Berkus
On 04/08/2014 03:53 PM, Robert Haas wrote: > In an ideal world, the kernel would put the hottest pages on the local > node and the less-hot pages on remote nodes, moving pages around as > the workload shifts. In practice, that's probably pretty hard. > Fortunately, it's not nearly as important as

Re: [PATCH 0/2] Disable zone_reclaim_mode by default

2014-04-08 Thread Robert Haas
On Tue, Apr 8, 2014 at 10:17 AM, Christoph Lameter wrote: > Another solution here would be to increase the threshhold so that > 4 socket machines do not enable zone reclaim by default. The larger the > NUMA system is the more memory is off node from the perspective of a > processor and the larger

Re: [PATCH 0/2] Disable zone_reclaim_mode by default

2014-04-08 Thread Josh Berkus
On 04/08/2014 10:17 AM, Christoph Lameter wrote: > Another solution here would be to increase the threshhold so that > 4 socket machines do not enable zone reclaim by default. The larger the > NUMA system is the more memory is off node from the perspective of a > processor and the larger the hit

Re: [PATCH 0/2] Disable zone_reclaim_mode by default

2014-04-08 Thread Andres Freund
On 2014-04-08 09:17:04 -0500, Christoph Lameter wrote: > On Tue, 8 Apr 2014, Vlastimil Babka wrote: > > > On 04/08/2014 12:34 AM, Mel Gorman wrote: > > > When it was introduced, zone_reclaim_mode made sense as NUMA distances > > > punished and workloads were generally partitioned to fit into a

Re: [PATCH 0/2] Disable zone_reclaim_mode by default

2014-04-08 Thread Christoph Lameter
On Tue, 8 Apr 2014, Vlastimil Babka wrote: > On 04/08/2014 12:34 AM, Mel Gorman wrote: > > When it was introduced, zone_reclaim_mode made sense as NUMA distances > > punished and workloads were generally partitioned to fit into a NUMA > > node. NUMA machines are now common but few of the

[PATCH 0/2] Disable zone_reclaim_mode by default v2

2014-04-08 Thread Mel Gorman
Changelog since v1 o topology comment updates When it was introduced, zone_reclaim_mode made sense as NUMA distances punished and workloads were generally partitioned to fit into a NUMA node. NUMA machines are now common but few of the workloads are NUMA-aware and it's routine to see major

Re: [PATCH 0/2] Disable zone_reclaim_mode by default

2014-04-08 Thread Vlastimil Babka
On 04/08/2014 12:34 AM, Mel Gorman wrote: When it was introduced, zone_reclaim_mode made sense as NUMA distances punished and workloads were generally partitioned to fit into a NUMA node. NUMA machines are now common but few of the workloads are NUMA-aware and it's routine to see major

Re: [PATCH 0/2] Disable zone_reclaim_mode by default

2014-04-08 Thread Vlastimil Babka
On 04/08/2014 12:34 AM, Mel Gorman wrote: When it was introduced, zone_reclaim_mode made sense as NUMA distances punished and workloads were generally partitioned to fit into a NUMA node. NUMA machines are now common but few of the workloads are NUMA-aware and it's routine to see major

[PATCH 0/2] Disable zone_reclaim_mode by default v2

2014-04-08 Thread Mel Gorman
Changelog since v1 o topology comment updates When it was introduced, zone_reclaim_mode made sense as NUMA distances punished and workloads were generally partitioned to fit into a NUMA node. NUMA machines are now common but few of the workloads are NUMA-aware and it's routine to see major

Re: [PATCH 0/2] Disable zone_reclaim_mode by default

2014-04-08 Thread Christoph Lameter
On Tue, 8 Apr 2014, Vlastimil Babka wrote: On 04/08/2014 12:34 AM, Mel Gorman wrote: When it was introduced, zone_reclaim_mode made sense as NUMA distances punished and workloads were generally partitioned to fit into a NUMA node. NUMA machines are now common but few of the workloads are

Re: [PATCH 0/2] Disable zone_reclaim_mode by default

2014-04-08 Thread Andres Freund
On 2014-04-08 09:17:04 -0500, Christoph Lameter wrote: On Tue, 8 Apr 2014, Vlastimil Babka wrote: On 04/08/2014 12:34 AM, Mel Gorman wrote: When it was introduced, zone_reclaim_mode made sense as NUMA distances punished and workloads were generally partitioned to fit into a NUMA

Re: [PATCH 0/2] Disable zone_reclaim_mode by default

2014-04-08 Thread Josh Berkus
On 04/08/2014 10:17 AM, Christoph Lameter wrote: Another solution here would be to increase the threshhold so that 4 socket machines do not enable zone reclaim by default. The larger the NUMA system is the more memory is off node from the perspective of a processor and the larger the hit from

Re: [PATCH 0/2] Disable zone_reclaim_mode by default

2014-04-08 Thread Robert Haas
On Tue, Apr 8, 2014 at 10:17 AM, Christoph Lameter c...@linux.com wrote: Another solution here would be to increase the threshhold so that 4 socket machines do not enable zone reclaim by default. The larger the NUMA system is the more memory is off node from the perspective of a processor and

Re: [PATCH 0/2] Disable zone_reclaim_mode by default

2014-04-08 Thread Josh Berkus
On 04/08/2014 03:53 PM, Robert Haas wrote: In an ideal world, the kernel would put the hottest pages on the local node and the less-hot pages on remote nodes, moving pages around as the workload shifts. In practice, that's probably pretty hard. Fortunately, it's not nearly as important as

Re: [PATCH 0/2] Disable zone_reclaim_mode by default

2014-04-08 Thread Christoph Lameter
On Tue, 8 Apr 2014, Robert Haas wrote: Well, as Josh quite rightly said, the hit from accessing remote memory is never going to be as large as the hit from disk. If and when there is a machine where remote memory is more expensive to access than disk, that's a good argument for

Re: [PATCH 0/2] Disable zone_reclaim_mode by default

2014-04-08 Thread Mel Gorman
On Tue, Apr 08, 2014 at 05:58:21PM -0500, Christoph Lameter wrote: On Tue, 8 Apr 2014, Robert Haas wrote: Well, as Josh quite rightly said, the hit from accessing remote memory is never going to be as large as the hit from disk. If and when there is a machine where remote memory is more

[PATCH 0/2] Disable zone_reclaim_mode by default

2014-04-07 Thread Mel Gorman
When it was introduced, zone_reclaim_mode made sense as NUMA distances punished and workloads were generally partitioned to fit into a NUMA node. NUMA machines are now common but few of the workloads are NUMA-aware and it's routine to see major performance due to zone_reclaim_mode being disabled

[PATCH 0/2] Disable zone_reclaim_mode by default

2014-04-07 Thread Mel Gorman
When it was introduced, zone_reclaim_mode made sense as NUMA distances punished and workloads were generally partitioned to fit into a NUMA node. NUMA machines are now common but few of the workloads are NUMA-aware and it's routine to see major performance due to zone_reclaim_mode being disabled