From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by smtp.lore.kernel.org (Postfix) with ESMTP id 51999C4167B for ; Mon, 26 Dec 2022 18:22:06 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id B43C34BB5E; Mon, 26 Dec 2022 13:22:05 -0500 (EST) X-Virus-Scanned: at lists.cs.columbia.edu Authentication-Results: mm01.cs.columbia.edu (amavisd-new); dkim=softfail (fail, message has been altered) header.i=@linux.dev Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id rXUtrvupVfb0; Mon, 26 Dec 2022 13:22:04 -0500 (EST) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 88B764BB25; Mon, 26 Dec 2022 13:22:04 -0500 (EST) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 3FE774BAC0 for ; Mon, 26 Dec 2022 13:22:03 -0500 (EST) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id BEivaXbhAd03 for ; Mon, 26 Dec 2022 13:22:02 -0500 (EST) Received: from out-67.mta0.migadu.com (out-67.mta0.migadu.com [91.218.175.67]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id E51A74BAB4 for ; Mon, 26 Dec 2022 13:22:01 -0500 (EST) Date: Mon, 26 Dec 2022 19:21:58 +0100 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1672078920; 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: in-reply-to:in-reply-to:references:references; bh=cj8fvcXIPRKjdcbdoKyucOKTny9ACesRtz6BgpVcVkM=; b=EIWyG69G/AZtzcWq5XIyBUSNRlQZDkyfc0U20LTF9fEMJl0FX0uOlJ/eAr9rqya/camTUG P+2F4Zq12xJ+DnTU/groB8gJHKmz/EnZ7/Oqqa66FkhngYxN7a/rJrXobamlTZBnn8glVM +7T7V3/Iiag3Ym7nSyg49j/ThSgmh2M= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Andrew Jones To: Colton Lewis Subject: Re: [kvm-unit-tests PATCH] arm: Remove MAX_SMP probe loop Message-ID: <20221226182158.3azk5zwvl2vsy36h@orel> References: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-Migadu-Flow: FLOW_OUT Cc: kvm@vger.kernel.org, maz@kernel.org, kvmarm@lists.cs.columbia.edu X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu On Tue, Dec 20, 2022 at 04:32:00PM +0000, Colton Lewis wrote: > Alexandru Elisei writes: > > > Though I'm not sure how you managed to get MAX_SMP to go down to 6 cores > > on > > a 12 core machine. MAX_SMP is initialized to $(getconf _NPROCESSORS_ONLN), > > so the body of the loop should never execute. I also tried it on a 6 core > > machine, and MAX_SMP was 6, not 3. > > > Am I missing something? > > To be clear, 12 cores was a simplified example I did not directly > verify. What happened to me was 152 cores being cut down to 4. I was > confused why one machine was running a test with 4 cores when my other > machines were running with 8 and traced it to that loop. In effect the > loop was doing MAX_SMP=floor(MAX_SMP / 2) until MAX_SMP <= 8. I printed > the iterations and MAX_SMP followed the sequence 152->76->38->19->9->4. Ah, I think I understand now. Were you running 32-bit arm tests? If so, it'd be good to point that out explicitly in the commit message (the 'arm:' prefix in the summary is ambiguous). Assuming the loop body was running because it needed to reduce MAX_SMP to 8 or lower for 32-bit arm tests, then we should be replacing the loop with something that caps MAX_SMP at 8 for 32-bit arm tests instead. Thanks, drew _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E76DDC4167B for ; Mon, 26 Dec 2022 18:22:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232195AbiLZSWL (ORCPT ); Mon, 26 Dec 2022 13:22:11 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37708 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231800AbiLZSWJ (ORCPT ); Mon, 26 Dec 2022 13:22:09 -0500 Received: from out-217.mta0.migadu.com (out-217.mta0.migadu.com [IPv6:2001:41d0:1004:224b::d9]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3815A1162 for ; Mon, 26 Dec 2022 10:22:05 -0800 (PST) Date: Mon, 26 Dec 2022 19:21:58 +0100 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1672078920; 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: in-reply-to:in-reply-to:references:references; bh=cj8fvcXIPRKjdcbdoKyucOKTny9ACesRtz6BgpVcVkM=; b=EIWyG69G/AZtzcWq5XIyBUSNRlQZDkyfc0U20LTF9fEMJl0FX0uOlJ/eAr9rqya/camTUG P+2F4Zq12xJ+DnTU/groB8gJHKmz/EnZ7/Oqqa66FkhngYxN7a/rJrXobamlTZBnn8glVM +7T7V3/Iiag3Ym7nSyg49j/ThSgmh2M= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Andrew Jones To: Colton Lewis Cc: Alexandru Elisei , kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu, maz@kernel.org, eric.auger@redhat.com, oliver.upton@linux.dev, reijiw@google.com, ricarkol@google.com Subject: Re: [kvm-unit-tests PATCH] arm: Remove MAX_SMP probe loop Message-ID: <20221226182158.3azk5zwvl2vsy36h@orel> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Tue, Dec 20, 2022 at 04:32:00PM +0000, Colton Lewis wrote: > Alexandru Elisei writes: > > > Though I'm not sure how you managed to get MAX_SMP to go down to 6 cores > > on > > a 12 core machine. MAX_SMP is initialized to $(getconf _NPROCESSORS_ONLN), > > so the body of the loop should never execute. I also tried it on a 6 core > > machine, and MAX_SMP was 6, not 3. > > > Am I missing something? > > To be clear, 12 cores was a simplified example I did not directly > verify. What happened to me was 152 cores being cut down to 4. I was > confused why one machine was running a test with 4 cores when my other > machines were running with 8 and traced it to that loop. In effect the > loop was doing MAX_SMP=floor(MAX_SMP / 2) until MAX_SMP <= 8. I printed > the iterations and MAX_SMP followed the sequence 152->76->38->19->9->4. Ah, I think I understand now. Were you running 32-bit arm tests? If so, it'd be good to point that out explicitly in the commit message (the 'arm:' prefix in the summary is ambiguous). Assuming the loop body was running because it needed to reduce MAX_SMP to 8 or lower for 32-bit arm tests, then we should be replacing the loop with something that caps MAX_SMP at 8 for 32-bit arm tests instead. Thanks, drew