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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Fri, 12 Apr 2019 07:04:11 +0100 Received: from b01ledav003.gho.pok.ibm.com (b01ledav003.gho.pok.ibm.com [9.57.199.108]) by b01cxnp23032.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x3C6499517563648 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 12 Apr 2019 06:04:10 GMT Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id D0731B205F; Fri, 12 Apr 2019 06:04:09 +0000 (GMT) Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 92B24B2065; Fri, 12 Apr 2019 06:04:09 +0000 (GMT) Received: from sofia.ibm.com (unknown [9.124.35.89]) by b01ledav003.gho.pok.ibm.com (Postfix) with ESMTP; Fri, 12 Apr 2019 06:04:09 +0000 (GMT) Received: by sofia.ibm.com (Postfix, from userid 1000) id BC1172E324D; Fri, 12 Apr 2019 11:34:06 +0530 (IST) Date: Fri, 12 Apr 2019 11:34:06 +0530 From: Gautham R Shenoy To: Nicholas Piggin Subject: Re: [PATCH v2] powerpc/watchdog: Use hrtimers for per-CPU heartbeat References: <20190409044005.26446-1-npiggin@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190409044005.26446-1-npiggin@gmail.com> User-Agent: Mutt/1.5.23 (2014-03-12) X-TM-AS-GCONF: 00 x-cbid: 19041206-0064-0000-0000-000003C9E778 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00010913; HX=3.00000242; KW=3.00000007; PH=3.00000004; SC=3.00000284; SDB=6.01187874; UDB=6.00622253; IPR=6.00968641; MB=3.00026405; MTD=3.00000008; XFM=3.00000015; UTC=2019-04-12 06:04:12 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19041206-0065-0000-0000-00003D08E69A Message-Id: <20190412060406.GA26155@in.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:, , definitions=2019-04-12_04:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1011 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=965 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1904120041 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: ego@linux.vnet.ibm.com Cc: "Gautham R . Shenoy" , Ravikumar Bangoria , linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Hello Nicholas, On Tue, Apr 09, 2019 at 02:40:05PM +1000, Nicholas Piggin wrote: > Using a jiffies timer creates a dependency on the tick_do_timer_cpu > incrementing jiffies. If that CPU has locked up and jiffies is not > incrementing, the watchdog heartbeat timer for all CPUs stops and > creates false positives and confusing warnings on local CPUs, and > also causes the SMP detector to stop, so the root cause is never > detected. > > Fix this by using hrtimer based timers for the watchdog heartbeat, > like the generic kernel hardlockup detector. > > Cc: Gautham R. Shenoy > Reported-by: Ravikumar Bangoria > Signed-off-by: Nicholas Piggin Looks good to me. Reviewed-by: Gautham R. Shenoy -- Thanks and Regards gautham.