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From: Paolo Bonzini <pbonzini@redhat.com>
To: Tristan Gingold <gingold@adacore.com>
Cc: qemu-devel@nongnu.org
Subject: [Qemu-devel] Re: [PATCH] Autodetect clock_gettime
Date: Tue, 15 Mar 2011 14:34:27 +0100	[thread overview]
Message-ID: <4D7F6AE3.7020301@redhat.com> (raw)
In-Reply-To: <1300195001-51765-1-git-send-email-gingold@adacore.com>

On 03/15/2011 02:16 PM, Tristan Gingold wrote:
> Some POSIX OSes (such as Darwin) doesn't have clock_gettime.  This patch
> falls back on gettimeofday if clock_gettime is not available.

This may be okay as a stopgap measure, but any sane porting target for 
QEMU should have a monotonic clock.  In fact, Darwin has it.

http://www.wand.net.nz/~smr26/wordpress/2009/01/19/monotonic-time-in-mac-os-x/ 
hints that code such as the following should work and return nanoseconds:

#import <mach/mach_time.h>

     uint64_t t = mach_absolute_time();
     static mach_timebase_info_data_t info;
     if (info.denom == 0) {
         mach_timebase_info(&info);
     }
     return muldiv64(t, info.numer, info.denom);

Paolo

  reply	other threads:[~2011-03-15 13:34 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-03-15 13:16 [Qemu-devel] [PATCH] Autodetect clock_gettime Tristan Gingold
2011-03-15 13:34 ` Paolo Bonzini [this message]
2011-03-15 13:47   ` [Qemu-devel] " Tristan Gingold
2011-03-15 13:58     ` Paolo Bonzini
2011-03-15 14:17       ` Tristan Gingold

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