From owner-svn-src-head@freebsd.org Mon Nov 27 06:07:05 2017 Return-Path: Delivered-To: svn-src-head@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id BEA5FDF9FE3; Mon, 27 Nov 2017 06:07:05 +0000 (UTC) (envelope-from nwhitehorn@freebsd.org) Received: from c.mail.sonic.net (c.mail.sonic.net [64.142.111.80]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id AB6AE654B9; Mon, 27 Nov 2017 06:07:05 +0000 (UTC) (envelope-from nwhitehorn@freebsd.org) Received: from comporellon.tachypleus.net (cpe-75-82-218-62.socal.res.rr.com [75.82.218.62]) (authenticated bits=0) by c.mail.sonic.net (8.15.1/8.15.1) with ESMTPSA id vAR66upx031049 (version=TLSv1.2 cipher=DHE-RSA-AES128-SHA bits=128 verify=NOT); Sun, 26 Nov 2017 22:06:57 -0800 Subject: Re: svn commit: r326218 - head/sys/kern To: John Baldwin Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org References: <201711252341.vAPNf5Qx001464@repo.freebsd.org> <3170692.kvv90QqB0X@ralph.baldwin.cx> From: Nathan Whitehorn Message-ID: Date: Sun, 26 Nov 2017 22:06:56 -0800 User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:52.0) Gecko/20100101 Thunderbird/52.5.0 MIME-Version: 1.0 In-Reply-To: <3170692.kvv90QqB0X@ralph.baldwin.cx> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-Sonic-CAuth: UmFuZG9tSVagWHczlbvJRDm0AMTcXUN6Kw+98q+0DBDpaFwCBJt2AgHb44cMcM/ocXU1FFaS0eV9YTuzYL6mICnGBZoOrrubOnA7STh6Cfw= X-Sonic-ID: C;UKBqLDnT5xGY9+snWtmBlw== M;nGbLLDnT5xGY9+snWtmBlw== X-Spam-Flag: No X-Sonic-Spam-Details: 0.0/5.0 by cerberusd X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.25 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 27 Nov 2017 06:07:05 -0000 On 11/26/17 20:50, John Baldwin wrote: > On Saturday, November 25, 2017 11:41:05 PM Nathan Whitehorn wrote: >> Author: nwhitehorn >> Date: Sat Nov 25 23:41:05 2017 >> New Revision: 326218 >> URL: https://svnweb.freebsd.org/changeset/base/326218 >> >> Log: >> Remove some, but not all, assumptions that the BSP is CPU 0 and that CPUs >> are numbered densely from there to n_cpus. >> >> MFC after: 1 month >> >> Modified: >> head/sys/kern/kern_clock.c >> head/sys/kern/kern_clocksource.c >> head/sys/kern/kern_shutdown.c >> head/sys/kern/kern_timeout.c >> head/sys/kern/sched_ule.c >> head/sys/kern/subr_pcpu.c >> >> Modified: head/sys/kern/kern_clock.c >> ============================================================================== >> --- head/sys/kern/kern_clock.c Sat Nov 25 23:23:24 2017 (r326217) >> +++ head/sys/kern/kern_clock.c Sat Nov 25 23:41:05 2017 (r326218) >> @@ -573,7 +573,9 @@ hardclock_cnt(int cnt, int usermode) >> void >> hardclock_sync(int cpu) >> { >> - int *t = DPCPU_ID_PTR(cpu, pcputicks); >> + int *t; >> + KASSERT(!CPU_ABSENT(cpu), ("Absent CPU %d", cpu)); > Blank line before the KASSERT() perhaps? > >> + t = DPCPU_ID_PTR(cpu, pcputicks); >> >> *t = ticks; > Probably don't need this blank line though? Those are both good ideas. > >> } >> >> Modified: head/sys/kern/sched_ule.c >> ============================================================================== >> --- head/sys/kern/sched_ule.c Sat Nov 25 23:23:24 2017 (r326217) >> +++ head/sys/kern/sched_ule.c Sat Nov 25 23:41:05 2017 (r326218) >> @@ -2444,6 +2451,7 @@ sched_add(struct thread *td, int flags) >> * Pick the destination cpu and if it isn't ours transfer to the >> * target cpu. >> */ >> + td_get_sched(td)->ts_cpu = curcpu; /* Pick something valid to start */ >> cpu = sched_pickcpu(td, flags); > It is not obvious why every sched_add() needs this once you've fixed thread0. > Shouldn't new threads just inherit from thread0's already-fixed value? If not, > perhaps fix thread0's value sooner? That's a fair point. I don't remember the rationale for this now; the changes are over a year old from the powernv branch. I do remember setting thread0's CPU early not working, but have forgotten why. I will try to remember... >> tdq = sched_setcpu(td, cpu, flags); >> tdq_add(tdq, td, flags); >> >> Modified: head/sys/kern/subr_pcpu.c >> ============================================================================== >> --- head/sys/kern/subr_pcpu.c Sat Nov 25 23:23:24 2017 (r326217) >> +++ head/sys/kern/subr_pcpu.c Sat Nov 25 23:41:05 2017 (r326218) >> @@ -279,6 +279,8 @@ pcpu_destroy(struct pcpu *pcpu) >> struct pcpu * >> pcpu_find(u_int cpuid) >> { >> + KASSERT(cpuid_to_pcpu[cpuid] != NULL, >> + ("Getting uninitialized PCPU %d", cpuid)); > This KASSERT seems unnecessary? If the caller uses an invalid one, it will > just fault anyway. It won't necessarily fault. For example, on PowerPC, NULL is a valid address that does not trigger faults. It's unfortunately quite complicated to fix this in a general way. Even if it did fault, this makes the fault more informative (and has found at least one bug on arm64 already). > >> return (cpuid_to_pcpu[cpuid]); >> } >> @@ -409,7 +411,7 @@ DB_SHOW_ALL_COMMAND(pcpu, db_show_cpu_all) >> int id; >> >> db_printf("Current CPU: %d\n\n", PCPU_GET(cpuid)); >> - for (id = 0; id <= mp_maxid; id++) { >> + CPU_FOREACH(id) { > If you remove the KASSERT you don't need this change since it checks the return > value of pcpu_find() (which you didn't change). In particular, this DDB command > shows all valid pcpu structures safely even if that set is inconsistent with > the all_cpus mask (or the old version did at least). There is also nothing about > this that assumes BSP == 0 either. CPU_FOREACH() is doing a loop from 0 to > mp_maxid under the covers as well. True. CPU_FOREACH just seemed simpler here and future-proof if it ever started doing something more complex. -Nathan > >> pc = pcpu_find(id); >> if (pc != NULL) { >> show_pcpu(pc); >> >