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Wysocki" , Pavel Machek , Len Brown , Greg Kroah-Hartman , Alexander Viro , Christian Brauner , Jan Kara , saravanak@google.com, Manish Varma , Kelly Rossmoyer , kernel-team@android.com, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH v5] fs: Improve eventpoll logging to stop indicting timerfd Message-ID: References: <20240606172813.2755930-1-isaacmanjarres@google.com> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Mon, Jun 24, 2024 at 11:03:43AM -0700, John Stultz wrote: > On Thu, Jun 6, 2024 at 10:28 AM 'Isaac J. Manjarres' via kernel-team > wrote: > > > > From: Manish Varma > > > > timerfd doesn't create any wakelocks, but eventpoll can. When it does, > > it names them after the underlying file descriptor, and since all > > timerfd file descriptors are named "[timerfd]" (which saves memory on > > systems like desktops with potentially many timerfd instances), all > > wakesources created as a result of using the eventpoll-on-timerfd idiom > > are called... "[timerfd]". > > > > However, it becomes impossible to tell which "[timerfd]" wakesource is > > affliated with which process and hence troubleshooting is difficult. > > While your explanation above is understandable, I feel like it might > benefit from a more concrete example to show why this is problematic? > It feels like the description gets into the weeds pretty quickly and > makes it hard to understand the importance of the change. > > Again the N:P.F mapping is clear, but maybe including a specific > before and after example would help? > > Additionally, once you have this better named wakesource, can you > provide a specific example to illustrate a bit on how this > specifically helps the troubleshooting that was difficult before? > > thanks > -john Hi John, Thanks for your feedback on this! I'm more than happy to add more details to the commit text. I'll go ahead and add an example to showcase a scenario where the proposed changes make debugging easier. I'll send out v6 of the patch soon. --Isaac