Re: [PATCH] use unlikely() for current_kernel_time() loop
- From: Andi Kleen <ak@xxxxxxx>
- Date: Thu, 8 Jun 2006 07:39:33 +0200
On Thursday 08 June 2006 07:01, Andrew Morton wrote:
On 08 Jun 2006 04:28:12 +0200
Andi Kleen <ak@xxxxxxx> wrote:
Andreas Dilger <adilger@xxxxxxxxxxxxx> writes:
Hello,
I just noticed this minor optimization. current_kernel_time() is called
from current_fs_time() so it is used fairly often but it doesn't use
unlikely(read_seqretry(&xtime_lock, seq)) as other users of xtime_lock do.
Also removes extra whitespace on the empty line above.
It would be better to put the unlikely into the read_seqretry I guess.
yup. But it'd be good to check that this actually causes the compiler to
do the right thing, rather than simply ignoring it.
If it was put into a macro wrapper it should be safe enough.
I'm not sure how one would do that though. I guess compare
before-and-after assembly code, work out if "after" is better.
Nothing on x86-64 at least - it uses -fno-reorder-blocks by default.
-Andi
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
- Follow-Ups:
- Re: [PATCH] use unlikely() for current_kernel_time() loop
- From: Brian F. G. Bidulock
- Re: [PATCH] use unlikely() for current_kernel_time() loop
- References:
- [PATCH] use unlikely() for current_kernel_time() loop
- From: Andreas Dilger
- Re: [PATCH] use unlikely() for current_kernel_time() loop
- From: Andi Kleen
- Re: [PATCH] use unlikely() for current_kernel_time() loop
- From: Andrew Morton
- [PATCH] use unlikely() for current_kernel_time() loop
- Prev by Date: [PATCH] 9pfs: missing result check in v9fs_vfs_readlink() and v9fs_vfs_link()
- Next by Date: Re: 2.6.17-rc6-mm1
- Previous by thread: Re: [PATCH] use unlikely() for current_kernel_time() loop
- Next by thread: Re: [PATCH] use unlikely() for current_kernel_time() loop
- Index(es):
Relevant Pages
|
|
