From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.skyhub.de (mail.skyhub.de [5.9.137.197]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B01D62F3A for ; Wed, 4 May 2022 21:01:15 +0000 (UTC) Received: from zn.tnic (p5de8eeb4.dip0.t-ipconnect.de [93.232.238.180]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id 9D53E1EC0354; Wed, 4 May 2022 23:01:09 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1651698069; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:in-reply-to:in-reply-to: references:references; bh=CVQhTFxBk4LR/y/BsUV+TEsrpPonN5g3FeS0pnSesIg=; b=PgdoSq+mYUSotajou9NuBD5oB9gB1N5TMOLRDCPzZaD4gNOLPYQD0kanV60FeW1IBxGQZm hpZsQi6FZJLf2tO6+mN4KInMJLLy3l316tMSK8JPZL6EyFLaQxbvz4P6gohtI2fBQNI3Xm SsgDtXan3Yu5yDmWJ0gjaUjVmD9wpnM= Date: Wed, 4 May 2022 23:01:08 +0200 From: Borislav Petkov To: Linus Torvalds Cc: Mark Hemment , Andrew Morton , the arch/x86 maintainers , Peter Zijlstra , patrice.chotard@foss.st.com, Mikulas Patocka , Lukas Czerner , Christoph Hellwig , "Darrick J. Wong" , Chuck Lever , Hugh Dickins , patches@lists.linux.dev, Linux-MM , mm-commits@vger.kernel.org, Mel Gorman Subject: Re: [patch 02/14] tmpfs: fix regressions from wider use of ZERO_PAGE Message-ID: References: Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: On Wed, May 04, 2022 at 01:40:07PM -0700, Linus Torvalds wrote: > Sadly, I'm on Zen2 with my 3970X, and the Zen 3 threadrippers seem to > be basically impossible to get. Yeah, what we did is get a gigabyte board: [ 0.000000] DMI: GIGABYTE MZ32-AR0-00/MZ32-AR0-00, BIOS M06 07/10/2021 and stick a server CPU in it: [ 2.352371] smpboot: CPU0: AMD EPYC 7313 16-Core Processor (family: 0x19, model: 0x1, stepping: 0x1) so that we can have the memory encryption stuff. 32 threads is fairly decent and kernel builds are fast enough, at least for me. If you need to do a lot of allmodconfigs, you probably need something bigger though. > Oh, the clear_user() in the ELF loader? I wouldn't have expected that > to be noticeable. Yah, that guy in load_elf_binary(). At least it did hit my breakpoint fairly often so I thought, what is a benchmark that does create a lot of processes... > Now, clear_page() is *very* noticeable, but that has its own special > magic and doesn't use clear_user(). Yeah, that's with the alternative CALL thing. Could be useful to try to see how much the inlined rep; movsb would bring... > Maybe there is some other clear_user() case I never thought of. My > dim memories of profiles definitely had copy_to_user, clear_page and > copy_page being some of the top copy loops. I could try to do a perf probe or whatever fancy new thing we do now on clear_user to get some numbers of how many times it gets called during the benchmark run. Or do you wanna know the callers too? Thx. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette