On 2012/2/23 7:42, Jilles Tjoelker wrote:
On Wed, Feb 22, 2012 at 03:22:50AM +0000, David Xu wrote:
Author: davidxu
Date: Wed Feb 22 03:22:49 2012
New Revision: 231989
URL: http://svn.freebsd.org/changeset/base/231989
Log:
Use unused fourth argument of umtx_op to pass flags to kernel for operation
UMTX_OP_WAIT. Upper 16bits is enough to hold a clock id, and lower
16bits is used to pass flags. The change saves a clock_gettime() syscall
from libthr.
Modified:
head/lib/libthr/thread/thr_umtx.c
head/sys/kern/kern_umtx.c
head/sys/sys/umtx.h
Modified: head/lib/libthr/thread/thr_umtx.c
==============================================================================
--- head/lib/libthr/thread/thr_umtx.c Wed Feb 22 01:50:13 2012
(r231988)
+++ head/lib/libthr/thread/thr_umtx.c Wed Feb 22 03:22:49 2012
(r231989)
@@ -200,20 +200,10 @@ int
+ abstime != NULL ? (void *)(uintptr_t)((clockid<< 16) |
UMTX_WAIT_ABSTIME) : 0,
Please check that this shift does not lose any information (i.e.,
clockid>= 0&& clockid<= 0xFFFF) before doing it.
Implementing clock_getcpuclockid() will require clockids greater than
65535 because such clockids contain a process id.
In which document said the clock id includes a process id ? I think the
clock_getcpuclockid()
is a simplified version of getrusage().
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