linux/arch/arm
Hugh Dickins 4c21e2f244 [PATCH] mm: split page table lock
Christoph Lameter demonstrated very poor scalability on the SGI 512-way, with
a many-threaded application which concurrently initializes different parts of
a large anonymous area.

This patch corrects that, by using a separate spinlock per page table page, to
guard the page table entries in that page, instead of using the mm's single
page_table_lock.  (But even then, page_table_lock is still used to guard page
table allocation, and anon_vma allocation.)

In this implementation, the spinlock is tucked inside the struct page of the
page table page: with a BUILD_BUG_ON in case it overflows - which it would in
the case of 32-bit PA-RISC with spinlock debugging enabled.

Splitting the lock is not quite for free: another cacheline access.  Ideally,
I suppose we would use split ptlock only for multi-threaded processes on
multi-cpu machines; but deciding that dynamically would have its own costs.
So for now enable it by config, at some number of cpus - since the Kconfig
language doesn't support inequalities, let preprocessor compare that with
NR_CPUS.  But I don't think it's worth being user-configurable: for good
testing of both split and unsplit configs, split now at 4 cpus, and perhaps
change that to 8 later.

There is a benefit even for singly threaded processes: kswapd can be attacking
one part of the mm while another part is busy faulting.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 21:40:42 -07:00
..
boot [PATCH] type fix in arm/boot/compressed/misc.c 2005-10-29 10:35:08 -07:00
common [PATCH] DRIVER MODEL: Get rid of the obsolete tri-level suspend/resume callbacks 2005-10-28 09:52:56 -07:00
configs [ARM] 2918/1: [update] Base port of Comdial MP1000 platfrom 2005-10-28 16:19:37 +01:00
kernel [PATCH] mm: arm ready for split ptlock 2005-10-29 21:40:42 -07:00
lib [ARM] 2930/1: optimized sha1 implementation for ARM 2005-10-28 15:26:40 +01:00
mach-aaec2000 [ARM] 3042/1: AAED-2000 - LCD panel informations 2005-10-28 16:51:44 +01:00
mach-clps711x [ARM] 2918/1: [update] Base port of Comdial MP1000 platfrom 2005-10-28 16:19:37 +01:00
mach-clps7500 [ARM] 2994/1: Replace map_desc.physical with map_desc.pfn: CLPS7500 2005-10-28 15:19:05 +01:00
mach-ebsa110 [ARM] 2997/1: Replace map_desc.physical with map_desc.pfn: EBSA110 2005-10-28 15:19:08 +01:00
mach-epxa10db [ARM] 2996/1: Replace map_desc.physical with map_desc.pfn: EPXA10DB 2005-10-28 15:19:07 +01:00
mach-footbridge [ARM] 2998/1: Replace map_desc.physical with map_desc.pfn: Footbridge 2005-10-28 15:19:08 +01:00
mach-h720x [ARM] 2999/1: Replace map_desc.physical with map_desc.pfn: H720x 2005-10-28 15:19:09 +01:00
mach-imx [ARM] 3000/1: Replace map_desc.physical with map_desc.pfn: iMX 2005-10-28 15:19:10 +01:00
mach-integrator [ARM] 3001/1: Replace map_desc.physical with map_desc.pfn: Integrator 2005-10-28 15:19:10 +01:00
mach-iop3xx [ARM] 2983/1: Replace map_desc.physical with map_desc.pfn: IOP3xx 2005-10-28 15:18:57 +01:00
mach-ixp4xx [ARM] 2985/1: Replace map_desc.physical with map_desc.pfn: IXP4xx 2005-10-28 15:18:59 +01:00
mach-ixp2000 [ARM] 2984/1: Replace map_desc.physical with map_desc.pfn: IXP2000 2005-10-28 15:18:58 +01:00
mach-l7200 [ARM] 2980/1: Fix L7200 core.c compile 2005-10-14 12:49:15 +01:00
mach-lh7a40x [ARM] 2986/1: Replace map_desc.physical with map_desc.pfn: LH7A40x 2005-10-28 15:18:59 +01:00
mach-omap1 [ARM] 2987/1: Replace map_desc.physical with map_desc.pfn: OMAP 2005-10-28 15:19:00 +01:00
mach-pxa Merge ../bleed-2.6 2005-10-28 10:13:16 -07:00
mach-rpc [ARM] 2989/1: Replace map_desc.physical with map_desc.pfn: RiscPC 2005-10-28 15:19:02 +01:00
mach-s3c2410 [ARM] 3047/1: SMDK2440 - add framebuffer platform data 2005-10-28 15:31:47 +01:00
mach-sa1100 [ARM] Add support for SA1100 Jornada flash device support 2005-10-29 16:09:59 +01:00
mach-shark [ARM] 2991/1: Replace map_desc.physical with map_desc.pfn: Shark 2005-10-28 15:19:03 +01:00
mach-versatile [ARM] 2995/1: Replace map_desc.physical with map_desc.pfn: Versatile 2005-10-28 15:19:06 +01:00
mm [PATCH] mm: split page table lock 2005-10-29 21:40:42 -07:00
nwfpe [ARM] 2978/1: nwfpe - clean up sparse errors 2005-10-12 19:58:10 +01:00
oprofile [PATCH] mm: kill check_user_page_readable 2005-10-29 21:40:41 -07:00
plat-omap [ARM] 2987/1: Replace map_desc.physical with map_desc.pfn: OMAP 2005-10-28 15:19:00 +01:00
tools [ARM] Update mach-types 2005-10-10 09:48:10 +01:00
vfp kbuild: arm - use generic asm-offsets.h support 2005-09-09 21:08:59 +02:00
Kconfig [ARM] 3041/1: AAEC-2000 - CLCD controller platform glue 2005-10-28 16:51:44 +01:00
Kconfig.debug [ARM] Fix typo in arch/arm/Kconfig.debug 2005-09-09 15:57:17 +01:00
Makefile [ARM] 3061/1: cleanup the XIP link address mess 2005-10-29 21:44:56 +01:00