Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755175Ab0H0SFi (ORCPT ); Fri, 27 Aug 2010 14:05:38 -0400 Received: from thoth.sbs.de ([192.35.17.2]:17236 "EHLO thoth.sbs.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752159Ab0H0SFf (ORCPT ); Fri, 27 Aug 2010 14:05:35 -0400 Message-ID: <4C77FE57.7050105@siemens.com> Date: Fri, 27 Aug 2010 20:05:11 +0200 From: Jan Kiszka User-Agent: Mozilla/5.0 (X11; U; Linux i686 (x86_64); de; rv:1.8.1.12) Gecko/20080226 SUSE/2.0.0.12-1.1 Thunderbird/2.0.0.12 Mnenhy/0.7.5.666 MIME-Version: 1.0 To: Zachary Amsden CC: kvm@vger.kernel.org, Avi Kivity , Marcelo Tosatti , Glauber Costa , Thomas Gleixner , John Stultz , linux-kernel@vger.kernel.org Subject: Re: [KVM timekeeping 17/35] Implement getnsboottime kernel API References: <1282291669-25709-1-git-send-email-zamsden@redhat.com> <1282291669-25709-18-git-send-email-zamsden@redhat.com> In-Reply-To: <1282291669-25709-18-git-send-email-zamsden@redhat.com> Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2962 Lines: 83 Zachary Amsden wrote: > Add a kernel call to get the number of nanoseconds since boot. This > is generally useful enough to make it a generic call. > > Signed-off-by: Zachary Amsden > --- > include/linux/time.h | 1 + > kernel/time/timekeeping.c | 27 +++++++++++++++++++++++++++ > 2 files changed, 28 insertions(+), 0 deletions(-) > > diff --git a/include/linux/time.h b/include/linux/time.h > index ea3559f..5d04108 100644 > --- a/include/linux/time.h > +++ b/include/linux/time.h > @@ -145,6 +145,7 @@ extern void getnstimeofday(struct timespec *tv); > extern void getrawmonotonic(struct timespec *ts); > extern void getboottime(struct timespec *ts); > extern void monotonic_to_bootbased(struct timespec *ts); > +extern s64 getnsboottime(void); > > extern struct timespec timespec_trunc(struct timespec t, unsigned gran); > extern int timekeeping_valid_for_hres(void); > diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c > index caf8d4d..d250f0a 100644 > --- a/kernel/time/timekeeping.c > +++ b/kernel/time/timekeeping.c > @@ -285,6 +285,33 @@ void ktime_get_ts(struct timespec *ts) > } > EXPORT_SYMBOL_GPL(ktime_get_ts); > > + > +/** > + * getnsboottime - get the bootbased clock in nsec format > + * > + * The function calculates the bootbased clock from the realtime > + * clock and the wall_to_monotonic offset and stores the result > + * in normalized timespec format in the variable pointed to by @ts. > + */ This thing is not returning anything in some ts variable. And I also had a hard time spotting the key difference to getboottime - the name is really confusing. Besides this, if you have good suggestion how to provide a compat version for older kernels, I'm all ears. Please also have a careful look at kvm-kmod's kvm_getboottime again, right now I'm a bit confused about what it is supposed to return and what it actually does (note that kvm-kmod cannot account for time spent in suspend state). Thanks! Jan > +s64 getnsboottime(void) > +{ > + unsigned int seq; > + s64 secs, nsecs; > + > + WARN_ON(timekeeping_suspended); > + > + do { > + seq = read_seqbegin(&xtime_lock); > + secs = xtime.tv_sec + wall_to_monotonic.tv_sec; > + secs += total_sleep_time.tv_sec; > + nsecs = xtime.tv_nsec + wall_to_monotonic.tv_nsec; > + nsecs += total_sleep_time.tv_nsec + timekeeping_get_ns(); > + > + } while (read_seqretry(&xtime_lock, seq)); > + return nsecs + (secs * NSEC_PER_SEC); > +} > +EXPORT_SYMBOL_GPL(getnsboottime); > + > /** > * do_gettimeofday - Returns the time of day in a timeval > * @tv: pointer to the timeval to be set -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/