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t=1781867497; bh=iJOKcZvygsqgxm7muAKd+76uHoZFFY5TClZKa0FpZrc=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=i02R1fLGWodVSipWVNcr/NHtzTLSPn4Vwoo5KZnlFsrozVruc5I1skirY/Hh6Yc9L 8R+b7OuoNsli3otBv8hqVAmkK/Df76UWA2/NwJ9UnxH77HoXlL2rx8gGZhzHsF38mZ MirD6gCLvbH0teVyfEPwjZvLGN1q9I7kMqQC6MebmoI21QQSVKyAlHvx8JJ12KW0W0 Tx+Uo3E+Q/kLwCjBHoqk2IJ7f9vdtFfVFGcKRUNXhHJ7QcRnGz3gbukp8xjcoVKEte MJegk+tCRGtXs1nfC9l0Mx3DQAcJnT14ZrOoVUzxT0FVbx11etk/prYlwB+dtlrhbU 47iIEXXmJfNJA== Date: Fri, 19 Jun 2026 12:11:31 +0100 From: Lorenzo Stoakes To: Pedro Falcato Cc: Suren Baghdasaryan , Jan Kara , kernel test robot , Frederick Mayle , oe-lkp@lists.linux.dev, lkp@intel.com, Andrew Morton , Kalesh Singh , David Hildenbrand , Matthew Wilcox , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [linux-next:master] [mm] 7b32f64bc5: pts.svt-av1.Preset13.Bosphorus4K.frames_per_second 45.8% regression Message-ID: References: <202606181547.617a6967-lkp@intel.com> <6z2rqmo7b6m2rdhqurspwya25ps4dj7lctdygnmq3rn4xt6h3i@57kiiy72epgd> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 915F140004 X-Stat-Signature: bx9u48ffdkwoqm97nffoa1ssm7buy4tk X-HE-Tag: 1781867498-108932 X-HE-Meta: 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 0FwSymXK HtQRwbb8GdvfYifBd/KiNemcgPyHJTVcaQ7C2F7oZRL82Pi29vVEDsxXnF27zY8QRUmrmPZbOJyAXzhblRa0AdYAkJMIG9uZFSF3hxEFnv2qRfVZoOXxGJvQNkoq/ebEsRJluf+cbRcWB02Ef60UOqVdSQGBbp5eObLmCTciFNMyEIjpEoh1GzQdeEbEpGj7m32Ht4piy1mSol4qomz/438qPKU+enraFGNL+gIrn5I6Edr2CpDQZUriJoVdg6N1F5zxXgR3DKwxVYwetazeLwSoApb7Wk73fpaxG/YXv1INn6yrZ5fiZu8v5RHmfQcXH1T6eJUBXGJFEaNDc68L3ZYC/cchsVIHE/nTr+l9CDBgErtRd453Llf+HkA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Jun 18, 2026 at 05:32:31PM +0100, Pedro Falcato wrote: > On Thu, Jun 18, 2026 at 04:03:43PM +0000, Suren Baghdasaryan wrote: > > On Thu, Jun 18, 2026 at 2:30 PM Lorenzo Stoakes wrote: > > > > > > On Thu, Jun 18, 2026 at 11:30:47AM +0200, Jan Kara wrote: > > > > On Thu 18-06-26 16:00:42, kernel test robot wrote: > > > > > Hello, > > > > > > > > > > kernel test robot noticed a 45.8% regression of pts.svt-av1.Preset13.Bosphorus4K.frames_per_second on: > > > > > > > > This one looks serious enough and real. It would be good to figure out what > > > > happens in this benchmark that it benefits from the readahead across VMA > > > > boundaries so much... > > > > > > I think a revert first no? This seems pretty huge for something that isn't key > > > to the kernel, then a new attempt can be tried with this issue addressed > > > perhaps? > > > > A quick search yields: "The > > pts.svt-av1.Preset13.Bosphorus4K.frames_per_second is a benchmarking > > metric from the Phoronix Test Suite that measures how many frames per > > second a CPU can encode using the open-source SVT-AV1 video encoder." > > > > If this is a video encoding benchmark I would expect it to explicitly > > prefetch the data from the disk before measuring the encoding speed. > > If limiting readahead caused this regression, I suspect the benchmark > > doesn't explicitly prefetch the data... > > Well, commonly video data doesn't actually fit in memory :) > > A quick look at the code (I think it's https://gitlab.com/AOMediaCodec/SVT-AV1/-/blob/master/Source/App/app_process_cmd.c#L821) > suggests it is progressively mapping the file data for a given frame > (or frames?). So the old behavior would result in page faults for a given > frame starting readahead for the next few frames. This looks reasonable. > > FWIW I suspected this was a really weird case regarding mprotect or > something, and I'm happy it isn't; but at least I had a suggestion for that - > for this, maybe dropping the change (for now?) is the best course of action. Am sending a revert. > > -- > Pedro Thanks, Lorenzo