diff options
author | Nick Piggin <npiggin@suse.de> | 2008-07-25 19:45:22 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-07-26 12:00:05 -0700 |
commit | 21cc199baa815d7b3f1ace4be20b9558cbddc00f (patch) | |
tree | eb4f3fa42a83613e2fe586b2555a811740952dce /arch/ia64/lib/flush.S | |
parent | a0a8f5364a5ad248aec6cb705e0092ff563edc2f (diff) |
mm: introduce get_user_pages_fast
Introduce a new get_user_pages_fast mm API, which is basically a
get_user_pages with a less general API (but still tends to be suited to
the common case):
- task and mm are always current and current->mm
- force is always 0
- pages is always non-NULL
- don't pass back vmas
This restricted API can be implemented in a much more scalable way on many
architectures when the ptes are present, by walking the page tables
locklessly (no mmap_sem or page table locks). When the ptes are not
populated, get_user_pages_fast() could be slower.
This is implemented locklessly on x86, and used in some key direct IO call
sites, in later patches, which provides nearly 10% performance improvement
on a threaded database workload.
Lots of other code could use this too, depending on use cases (eg. grep
drivers/). And it might inspire some new and clever ways to use it.
[akpm@linux-foundation.org: build fix]
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Dave Kleikamp <shaggy@austin.ibm.com>
Cc: Andy Whitcroft <apw@shadowen.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Dave Kleikamp <shaggy@austin.ibm.com>
Cc: Badari Pulavarty <pbadari@us.ibm.com>
Cc: Zach Brown <zach.brown@oracle.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Reviewed-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/ia64/lib/flush.S')
0 files changed, 0 insertions, 0 deletions