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McKenney" To: Jiri Wiesner Cc: Thomas Gleixner , Mel Gorman , LKML , Linux-Net Subject: Re: [RFC PATCH] clocksource: increase watchdog retries Message-ID: <20211102000934.GG880162@paulmck-ThinkPad-P17-Gen-1> Reply-To: paulmck@kernel.org References: <20211027164352.GA23273@incl> <20211027213829.GB880162@paulmck-ThinkPad-P17-Gen-1> <20211028162025.GA1068@incl> <20211028184209.GH880162@paulmck-ThinkPad-P17-Gen-1> <20211101102803.GA16089@incl> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211101102803.GA16089@incl> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Nov 01, 2021 at 11:28:03AM +0100, Jiri Wiesner wrote: > On Thu, Oct 28, 2021 at 11:42:09AM -0700, Paul E. McKenney wrote: > > On Thu, Oct 28, 2021 at 06:20:25PM +0200, Jiri Wiesner wrote: > > > On Wed, Oct 27, 2021 at 02:38:29PM -0700, Paul E. McKenney wrote: > > > > I had something like this pending, but people came up with other workloads > > > > that resulted in repeated delays. In those cases, it does not make sense > > > > to ever mark the affected clocksource unstable. This led me to the patch > > > > shown below, which splats after about 100 consecutive long-delay retries, > > > > but which avoids marking the clocksource unstable. This is queued on -rcu. > > > > > > > > Does this work for you? > > > > > > > > commit 9ec2a03bbf4bee3d9fbc02a402dee36efafc5a2d > > > > Author: Paul E. McKenney > > > > Date: Thu May 27 11:03:28 2021 -0700 > > > > > > > > clocksource: Forgive repeated long-latency watchdog clocksource reads > > > > > > Yes, it does. I have done 100 reboots of the testing machine (running > > > 5.15-rc5 with the above patch applied) and TSC was stable every time. I > > > am going to start a longer test of 300 reboots for good measure and > > > report back next week. J. > > > > Very good, and thank you for giving it a go! > > Thank you for the fix! It resolves several strange results we got in our performance testing. > > > If it passes the upcoming tests > > I have done 300 reboots of the testing machine. Again, TSC was stable every time. > > > may I have your Tested-by? > > Absolutely: > Tested-by: Jiri Wiesner Applied, thank you! Thanx, Paul