From: Christoph Lameter <cl@linux.com>
To: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: David Rientjes <rientjes@google.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: linux-kernel@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>
Subject: [slubllv6 12/17] slub: Avoid disabling interrupts in free slowpath
Date: Thu, 26 May 2011 13:14:54 -0500 [thread overview]
Message-ID: <20110526181508.302886720@linux.com> (raw)
In-Reply-To: 20110526181442.789868308@linux.com
[-- Attachment #1: slab_free_without_irqoff --]
[-- Type: text/plain, Size: 2060 bytes --]
Disabling interrupts can be avoided now. However, list operation still require
disabling interrupts since allocations can occur from interrupt
contexts and there is no way to perform atomic list operations.
The acquition of the list_lock therefore has to disable interrupts as well.
Dropping interrupt handling significantly simplifies the slowpath.
Signed-off-by: Christoph Lameter <cl@linux.com>
---
mm/slub.c | 16 +++++-----------
1 file changed, 5 insertions(+), 11 deletions(-)
Index: linux-2.6/mm/slub.c
===================================================================
--- linux-2.6.orig/mm/slub.c 2011-05-24 09:40:57.434875035 -0500
+++ linux-2.6/mm/slub.c 2011-05-24 09:41:00.194875015 -0500
@@ -2183,11 +2183,10 @@ static void __slab_free(struct kmem_cach
struct kmem_cache_node *n = NULL;
unsigned long flags;
- local_irq_save(flags);
stat(s, FREE_SLOWPATH);
if (kmem_cache_debug(s) && !free_debug_processing(s, page, x, addr))
- goto out_unlock;
+ return;
do {
prior = page->freelist;
@@ -2206,7 +2205,7 @@ static void __slab_free(struct kmem_cach
* Otherwise the list_lock will synchronize with
* other processors updating the list of slabs.
*/
- spin_lock(&n->list_lock);
+ spin_lock_irqsave(&n->list_lock, flags);
}
inuse = new.inuse;
@@ -2222,7 +2221,7 @@ static void __slab_free(struct kmem_cach
*/
if (was_frozen)
stat(s, FREE_FROZEN);
- goto out_unlock;
+ return;
}
/*
@@ -2245,11 +2244,7 @@ static void __slab_free(struct kmem_cach
stat(s, FREE_ADD_PARTIAL);
}
}
-
- spin_unlock(&n->list_lock);
-
-out_unlock:
- local_irq_restore(flags);
+ spin_unlock_irqrestore(&n->list_lock, flags);
return;
slab_empty:
@@ -2261,8 +2256,7 @@ slab_empty:
stat(s, FREE_REMOVE_PARTIAL);
}
- spin_unlock(&n->list_lock);
- local_irq_restore(flags);
+ spin_unlock_irqrestore(&n->list_lock, flags);
stat(s, FREE_SLAB);
discard_slab(s, page);
}
next prev parent reply other threads:[~2011-05-26 18:16 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-26 18:14 [slubllv6 00/17] SLUB: Lockless freelists for objects V6 Christoph Lameter
2011-05-26 18:14 ` [slubllv6 01/17] slub: Push irq disable into allocate_slab() Christoph Lameter
2011-05-26 22:13 ` David Rientjes
2011-05-31 16:55 ` Christoph Lameter
2011-05-26 18:14 ` [slubllv6 02/17] slub: Do not use frozen page flag but a bit in the page counters Christoph Lameter
2011-05-26 22:13 ` David Rientjes
2011-05-31 16:57 ` Christoph Lameter
2011-05-26 18:14 ` [slubllv6 03/17] slub: Move page->frozen handling near where the page->freelist handling occurs Christoph Lameter
2011-05-26 22:13 ` David Rientjes
2011-05-26 18:14 ` [slubllv6 04/17] x86: Add support for cmpxchg_double Christoph Lameter
2011-05-26 18:14 ` [slubllv6 05/17] mm: Rearrange struct page Christoph Lameter
2011-05-26 22:14 ` David Rientjes
2011-05-26 18:14 ` [slubllv6 06/17] slub: Add cmpxchg_double_slab() Christoph Lameter
2011-05-26 22:14 ` David Rientjes
2011-05-31 17:05 ` Christoph Lameter
2011-05-26 18:14 ` [slubllv6 07/17] slub: explicit list_lock taking Christoph Lameter
2011-05-26 22:15 ` David Rientjes
2011-05-31 17:11 ` Christoph Lameter
2011-05-27 19:40 ` David Rientjes
2011-05-26 18:14 ` [slubllv6 08/17] slub: Pass kmem_cache struct to lock and freeze slab Christoph Lameter
2011-05-27 19:43 ` David Rientjes
2011-05-26 18:14 ` [slubllv6 09/17] slub: Rework allocator fastpaths Christoph Lameter
2011-05-26 18:14 ` [slubllv6 10/17] slub: Invert locking and avoid slab lock Christoph Lameter
2011-05-26 18:14 ` [slubllv6 11/17] slub: Disable interrupts in free_debug processing Christoph Lameter
2011-05-26 18:14 ` Christoph Lameter [this message]
2011-05-26 22:16 ` [slubllv6 12/17] slub: Avoid disabling interrupts in free slowpath David Rientjes
2011-05-31 17:12 ` Christoph Lameter
2011-05-26 18:14 ` [slubllv6 13/17] slub: Get rid of the another_slab label Christoph Lameter
2011-05-26 18:14 ` [slubllv6 14/17] slub: Add statistics for the case that the current slab does not match the node Christoph Lameter
2011-05-26 18:14 ` [slubllv6 15/17] slub: fast release on full slab Christoph Lameter
2011-05-26 18:14 ` [slubllv6 16/17] slub: Not necessary to check for empty slab on load_freelist Christoph Lameter
2011-05-26 18:14 ` [slubllv6 17/17] slub: slabinfo update for cmpxchg handling Christoph Lameter
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