From: Dave Hansen <dave@sr71.net>
To: Mel Gorman <mgorman@suse.de>
Cc: Linux-MM <linux-mm@kvack.org>,
Johannes Weiner <hannes@cmpxchg.org>,
Christoph Lameter <cl@linux.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 18/22] mm: page allocator: Split magazine lock in two to reduce contention
Date: Thu, 09 May 2013 08:21:13 -0700 [thread overview]
Message-ID: <518BBEE9.7060800@sr71.net> (raw)
In-Reply-To: <1368028987-8369-19-git-send-email-mgorman@suse.de>
On 05/08/2013 09:03 AM, Mel Gorman wrote:
> @@ -368,10 +375,9 @@ struct zone {
>
> /*
> * Keep some order-0 pages on a separate free list
> - * protected by an irq-unsafe lock
> + * protected by an irq-unsafe lock.
> */
> - spinlock_t _magazine_lock;
> - struct free_area_magazine _noirq_magazine;
> + struct free_magazine noirq_magazine[NR_MAGAZINES];
Looks like pretty cool stuff!
The old per-cpu-pages stuff was all hung off alloc_percpu(), which
surely wasted lots of memory with many NUMA nodes. It's nice to see
this decoupled a bit from the online cpu count.
That said, the alloc_percpu() stuff is nice in how much it hides from
you when doing cpu hotplug. We'll _probably_ need this to be
dynamically-sized at some point, right?
> -static inline struct free_area_magazine *find_lock_magazine(struct zone *zone)
> +static inline struct free_magazine *lock_magazine(struct zone *zone)
> {
> - struct free_area_magazine *area = &zone->_noirq_magazine;
> - spin_lock(&zone->_magazine_lock);
> - return area;
> + int i = (raw_smp_processor_id() >> 1) & (NR_MAGAZINES-1);
> + spin_lock(&zone->noirq_magazine[i].lock);
> + return &zone->noirq_magazine[i];
> }
I bet this logic will be fun to play with once we have more magazines
around. For instance, on my system processors 0/80 are HT twins, so
they'd always be going after the same magazine. I guess that's a good
thing.
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WARNING: multiple messages have this Message-ID (diff)
From: Dave Hansen <dave@sr71.net>
To: Mel Gorman <mgorman@suse.de>
Cc: Linux-MM <linux-mm@kvack.org>,
Johannes Weiner <hannes@cmpxchg.org>,
Christoph Lameter <cl@linux.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 18/22] mm: page allocator: Split magazine lock in two to reduce contention
Date: Thu, 09 May 2013 08:21:13 -0700 [thread overview]
Message-ID: <518BBEE9.7060800@sr71.net> (raw)
In-Reply-To: <1368028987-8369-19-git-send-email-mgorman@suse.de>
On 05/08/2013 09:03 AM, Mel Gorman wrote:
> @@ -368,10 +375,9 @@ struct zone {
>
> /*
> * Keep some order-0 pages on a separate free list
> - * protected by an irq-unsafe lock
> + * protected by an irq-unsafe lock.
> */
> - spinlock_t _magazine_lock;
> - struct free_area_magazine _noirq_magazine;
> + struct free_magazine noirq_magazine[NR_MAGAZINES];
Looks like pretty cool stuff!
The old per-cpu-pages stuff was all hung off alloc_percpu(), which
surely wasted lots of memory with many NUMA nodes. It's nice to see
this decoupled a bit from the online cpu count.
That said, the alloc_percpu() stuff is nice in how much it hides from
you when doing cpu hotplug. We'll _probably_ need this to be
dynamically-sized at some point, right?
> -static inline struct free_area_magazine *find_lock_magazine(struct zone *zone)
> +static inline struct free_magazine *lock_magazine(struct zone *zone)
> {
> - struct free_area_magazine *area = &zone->_noirq_magazine;
> - spin_lock(&zone->_magazine_lock);
> - return area;
> + int i = (raw_smp_processor_id() >> 1) & (NR_MAGAZINES-1);
> + spin_lock(&zone->noirq_magazine[i].lock);
> + return &zone->noirq_magazine[i];
> }
I bet this logic will be fun to play with once we have more magazines
around. For instance, on my system processors 0/80 are HT twins, so
they'd always be going after the same magazine. I guess that's a good
thing.
next prev parent reply other threads:[~2013-05-09 15:21 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-05-08 16:02 [RFC PATCH 00/22] Per-cpu page allocator replacement prototype Mel Gorman
2013-05-08 16:02 ` Mel Gorman
2013-05-08 16:02 ` [PATCH 01/22] mm: page allocator: Lookup pageblock migratetype with IRQs enabled during free Mel Gorman
2013-05-08 16:02 ` Mel Gorman
2013-05-08 16:02 ` [PATCH 02/22] mm: page allocator: Push down where IRQs are disabled during page free Mel Gorman
2013-05-08 16:02 ` Mel Gorman
2013-05-08 16:02 ` [PATCH 03/22] mm: page allocator: Use unsigned int for order in more places Mel Gorman
2013-05-08 16:02 ` Mel Gorman
2013-05-08 16:02 ` [PATCH 04/22] mm: page allocator: Only check migratetype of pages being drained while CMA active Mel Gorman
2013-05-08 16:02 ` Mel Gorman
2013-05-08 16:02 ` [PATCH 05/22] oom: Use number of online nodes when deciding whether to suppress messages Mel Gorman
2013-05-08 16:02 ` Mel Gorman
2013-05-08 16:02 ` [PATCH 06/22] mm: page allocator: Convert hot/cold parameter and immediate callers to bool Mel Gorman
2013-05-08 16:02 ` Mel Gorman
2013-05-08 16:02 ` [PATCH 07/22] mm: page allocator: Do not lookup the pageblock migratetype during allocation Mel Gorman
2013-05-08 16:02 ` Mel Gorman
2013-05-08 16:02 ` [PATCH 08/22] mm: page allocator: Remove the per-cpu page allocator Mel Gorman
2013-05-08 16:02 ` Mel Gorman
2013-05-08 16:02 ` [PATCH 09/22] mm: page allocator: Allocate/free order-0 pages from a per-zone magazine Mel Gorman
2013-05-08 16:02 ` Mel Gorman
2013-05-08 18:41 ` Christoph Lameter
2013-05-08 18:41 ` Christoph Lameter
2013-05-09 15:23 ` Mel Gorman
2013-05-09 15:23 ` Mel Gorman
2013-05-09 16:21 ` Christoph Lameter
2013-05-09 16:21 ` Christoph Lameter
2013-05-09 17:27 ` Mel Gorman
2013-05-09 17:27 ` Mel Gorman
2013-05-09 18:08 ` Christoph Lameter
2013-05-09 18:08 ` Christoph Lameter
2013-05-08 16:02 ` [PATCH 10/22] mm: page allocator: Allocate and free pages from magazine in batches Mel Gorman
2013-05-08 16:02 ` Mel Gorman
2013-05-08 16:02 ` [PATCH 11/22] mm: page allocator: Shrink the magazine to the migratetypes in use Mel Gorman
2013-05-08 16:02 ` Mel Gorman
2013-05-08 16:02 ` [PATCH 12/22] mm: page allocator: Remove knowledge of hot/cold from page allocator Mel Gorman
2013-05-08 16:02 ` Mel Gorman
2013-05-08 16:02 ` [PATCH 13/22] mm: page allocator: Use list_splice to refill the magazine Mel Gorman
2013-05-08 16:02 ` Mel Gorman
2013-05-08 16:02 ` [PATCH 14/22] mm: page allocator: Do not disable IRQs just to update stats Mel Gorman
2013-05-08 16:02 ` Mel Gorman
2013-05-08 16:03 ` [PATCH 15/22] mm: page allocator: Check if interrupts are enabled only once per allocation attempt Mel Gorman
2013-05-08 16:03 ` Mel Gorman
2013-05-08 16:03 ` [PATCH 16/22] mm: page allocator: Remove coalescing improvement heuristic during page free Mel Gorman
2013-05-08 16:03 ` Mel Gorman
2013-05-08 16:03 ` [PATCH 17/22] mm: page allocator: Move magazine access behind accessors Mel Gorman
2013-05-08 16:03 ` Mel Gorman
2013-05-08 16:03 ` [PATCH 18/22] mm: page allocator: Split magazine lock in two to reduce contention Mel Gorman
2013-05-08 16:03 ` Mel Gorman
2013-05-09 15:21 ` Dave Hansen [this message]
2013-05-09 15:21 ` Dave Hansen
2013-05-15 19:44 ` Andi Kleen
2013-05-15 19:44 ` Andi Kleen
2013-05-08 16:03 ` [PATCH 19/22] mm: page allocator: Watch for magazine and zone lock contention Mel Gorman
2013-05-08 16:03 ` Mel Gorman
2013-05-08 16:03 ` [PATCH 20/22] mm: page allocator: Hold magazine lock for a batch of pages Mel Gorman
2013-05-08 16:03 ` Mel Gorman
2013-05-08 16:03 ` [PATCH 21/22] mm: compaction: Release free page list under a batched magazine lock Mel Gorman
2013-05-08 16:03 ` Mel Gorman
2013-05-08 16:03 ` [PATCH 22/22] mm: page allocator: Drain magazines for direct compact failures Mel Gorman
2013-05-08 16:03 ` Mel Gorman
2013-05-09 15:41 ` [RFC PATCH 00/22] Per-cpu page allocator replacement prototype Dave Hansen
2013-05-09 15:41 ` Dave Hansen
2013-05-09 16:25 ` Christoph Lameter
2013-05-09 16:25 ` Christoph Lameter
2013-05-09 17:33 ` Mel Gorman
2013-05-09 17:33 ` Mel Gorman
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