From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f51.google.com (mail-wm1-f51.google.com [209.85.128.51]) by mx.groups.io with SMTP id smtpd.web10.5882.1607036703464171560 for ; Thu, 03 Dec 2020 15:05:03 -0800 Authentication-Results: mx.groups.io; dkim=pass header.i=@linuxfoundation.org header.s=google header.b=CPPKpPRU; spf=pass (domain: linuxfoundation.org, ip: 209.85.128.51, mailfrom: richard.purdie@linuxfoundation.org) Received: by mail-wm1-f51.google.com with SMTP id h21so5490264wmb.2 for ; Thu, 03 Dec 2020 15:05:03 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=google; h=message-id:subject:from:to:date:in-reply-to:references:user-agent :mime-version:content-transfer-encoding; bh=943VdQFJjo/tNvIQHfue8DX+1S3baeC5SiQHBimDB7s=; b=CPPKpPRUo4W9YStWuaR1viWx1nn6P4aIiU6CGnCPRtmb/LpvLuLnlTHhw27Ob2oLk5 jhwXK8vH0Q2aeFTdxQQqk3cY0qGJhJqBYyEHJfoYR6fKd4FFEtvDk1vCbprOUd0dmoM/ /b/1/f+thozmm2bhQB1XAQIr9HoTSr4djNj3o= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:message-id:subject:from:to:date:in-reply-to :references:user-agent:mime-version:content-transfer-encoding; bh=943VdQFJjo/tNvIQHfue8DX+1S3baeC5SiQHBimDB7s=; b=SkCdm8DNg7lbiDw526EprpBnE3UjvMSveBLepy8qP1wuP+30Prg1apYAUbFXLvcjB1 CXhJmbinezUQ3qfEw9QDIqkeEbJ7QB5hLlldXuko/AR7S1Pap/B33jqLyCtyqCpjvQnb VyUJ2HBa8Uc7Ff6SbRizAA6Rqe3Az6WkPYfdCB4rLcGUjlkrg69bDwS0FK3O2sGx+2PS izR1NMuNqqsxAFL0jSCqm2I/7au3dCNQ34PtsXJ6xkGHxkYpfRAj64zz95VDEWcakZ1v QM7GpVlFxKSpbGdULPVgNCIb9X9HUDzLPbYiltWak2DaG6HMmK889EYGTE6AHjp+t4lI +UZA== X-Gm-Message-State: AOAM5309khEIXNvA9spPw0MjTZWDTEahZ9kTWonLTJNQSTj/YQYM8toa Fyk+lDYLJSEZosKsDjNksMKT8A== X-Google-Smtp-Source: ABdhPJxRvhmxlYZdC3xrOWq2RAR7nX3fsdB4tMfjOoXu/LxZZKSF43FvvlRum25OCpkrQLwMgiuEGg== X-Received: by 2002:a7b:c182:: with SMTP id y2mr1049345wmi.57.1607036701926; Thu, 03 Dec 2020 15:05:01 -0800 (PST) Return-Path: Received: from 9.2.d.8.e.2.1.e.1.8.2.c.7.a.4.c.c.3.f.5.a.b.a.0.0.b.8.0.1.0.0.2.ip6.arpa (9.2.d.8.e.2.1.e.1.8.2.c.7.a.4.c.c.3.f.5.a.b.a.0.0.b.8.0.1.0.0.2.ip6.arpa. [2001:8b0:aba:5f3c:c4a7:c281:e12e:8d29]) by smtp.gmail.com with ESMTPSA id o15sm1074070wrp.74.2020.12.03.15.05.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Dec 2020 15:05:01 -0800 (PST) Message-ID: <9335029ffaa0db7dff5bb0b4acea4ff381bf4b54.camel@linuxfoundation.org> Subject: Re: [OE-core] Automatic cap on BB_NUMBER_THREADS and PARALLEL_MAKE From: "Richard Purdie" To: Ross Burton , OE-core Date: Thu, 03 Dec 2020 23:05:00 +0000 In-Reply-To: References: User-Agent: Evolution 3.36.4-0ubuntu1 MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit On Thu, 2020-12-03 at 17:48 +0000, Ross Burton wrote: > Hi, > > Currently, BB_NUMBER_THREADS and PARALLEL_MAKE use the number of > cores > available unless told otherwise. This was a good idea six years > ago[1] but some modern machines are moving to very large core counts. > > For example, 88 core dual Xeons are fairly common. A ThunderX2 has > 256 > cores (2 sockets, 4 hyperthreads per physical core). The Ampere Altra > is dual socket 2*80=160 cores. > > At this level of parallelisation the sheer amount of I/O from the > unpack storm is quite excessive. As a strawman argument, I propose a > hard cap to the default BB_NUMBER_THREADS of -- and I'm literally > making up numbers here -- 32. Maybe 64. Comments? I've had no issues on 88 core systems. I'm not sure there is an "automatic" value we can guess at here and it is mentioned in local.conf for the user to customise... What might make more sense is to have site.conf from a user's homedir working better, although that does have issues of its own. I do agree with Alex that having bitbake throttle on system load would be nicer. Cheers, Richard