From mboxrd@z Thu Jan 1 00:00:00 1970 From: Keir Fraser Subject: Re: [Xen-users] Re: Xen 4 TSC problems Date: Thu, 18 Oct 2012 17:43:26 +0100 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Philippe.Simonet@swisscom.com, Ian.Campbell@citrix.com Cc: jeremy@goop.org, xen-devel@lists.xensource.com, dan.magenheimer@oracle.com, mrsanna1@gmail.com, olivier.hanesse@gmail.com, JBeulich@suse.com, xen-users@lists.xensource.com, mark@campbell-lange.net List-Id: xen-devel@lists.xenproject.org We have no idea yet whether this workaround even does any good. -- Keir On 18/10/2012 14:45, "Philippe.Simonet@swisscom.com" wrote: > in the meantime, it would be cool to have a kernel boot parameter that could > disable this wrapping' > correction' ? like > >> -----Original Message----- >> From: xen-devel-bounces@lists.xen.org [mailto:xen-devel- >> bounces@lists.xen.org] On Behalf Of Ian Campbell >> Sent: Thursday, October 18, 2012 9:40 AM >> To: Keir Fraser >> Cc: Jeremy Fitzhardinge; xen-devel@lists.xensource.com; Dan >> Magenheimer; Mauro; Olivier Hanesse; Jan Beulich; Xen Users; Mark Adams >> Subject: Re: [Xen-devel] [Xen-users] Re: Xen 4 TSC problems >> >> On Wed, 2012-10-17 at 17:15 +0100, Keir Fraser wrote: >>> @@ -540,6 +541,14 @@ static void plt_overflow(void *unused) >>> plt_wrap = __read_platform_stime(plt_stamp64 + plt_mask + 1); >>> if ( ABS(plt_wrap - now) > ABS(plt_now - now) ) >>> break; >>> + rdtscll(tsc); >>> + printk("XXX plt_overflow: plt_now=%"PRIx64" plt_wrap=%"PRIx64 >>> + " now=%"PRIx64" old_stamp=%"PRIx64" new_stamp=%"PRIx64 >>> + " plt_stamp64=%"PRIx64" plt_mask=%"PRIx64 >>> + " tsc=%"PRIx64" tsc_stamp=%"PRIx64"\n", >>> + plt_now, plt_wrap, now, old_stamp, plt_stamp, plt_stamp64, >>> + plt_mask, tsc, this_cpu(cpu_time).local_tsc_stamp); >>> + break; >> >> Is the break here, making the following update to plt_stamp64 dead code >> deliberate? >> >>> plt_stamp64 += plt_mask + 1; >>> } >>> if ( i != 0 ) >> >> Ian. >> >> >> >> _______________________________________________ >> Xen-devel mailing list >> Xen-devel@lists.xen.org >> http://lists.xen.org/xen-devel