From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx152.postini.com [74.125.245.152]) by kanga.kvack.org (Postfix) with SMTP id AA0266B0036 for ; Tue, 3 Sep 2013 04:44:22 -0400 (EDT) From: Vineet Gupta Subject: Re: ipc-msg broken again on 3.11-rc7? Date: Tue, 3 Sep 2013 08:44:17 +0000 Message-ID: References: <1372192414.1888.8.camel@buesod1.americas.hpqcorp.net> <1372202983.1888.22.camel@buesod1.americas.hpqcorp.net> <521DE5D7.4040305@synopsys.com> <52205597.3090609@synopsys.com> <5224BCF6.2080401@colorfullife.com> Content-Language: en-US Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Sender: owner-linux-mm@kvack.org List-ID: To: Manfred Spraul Cc: Linus Torvalds , Davidlohr Bueso , Sedat Dilek , Davidlohr Bueso , linux-next , LKML , Stephen Rothwell , Andrew Morton , linux-mm , Andi Kleen , Rik van Riel , Jonathan Gonzalez On 09/02/2013 09:59 PM, Manfred Spraul wrote:=0A= > Hi,=0A= >=0A= > [forgot to cc everyone, thus I'll summarize some mails...]=0A= > On 09/02/2013 06:58 AM, Vineet Gupta wrote:=0A= >> On 08/31/2013 11:20 PM, Linus Torvalds wrote:=0A= >>> Vineet, actual patch for what Davidlohr suggests attached. Can you try = it?=0A= >>>=0A= >>> Linus=0A= >> Apologies for late in getting back to this - I was away from my computer= for a bit.=0A= >>=0A= >> Unfortunately, with a quick test, this patch doesn't help.=0A= >> FWIW, this is latest mainline (.config attached).=0A= >>=0A= >> Let me know what diagnostics I can add to help with this.=0A= > msgctl08 is a bulk message send/receive test. I had to look at it once = =0A= > before, then it was a broken hardware:=0A= > https://lkml.org/lkml/2008/6/12/365=0A= > This can be ruled out, because it works with 3.10.=0A= >=0A= > msgctl08 uses pairs of threads: one thread does msgsnd(), the other one = =0A= > msgrcv().=0A= > There is no synchronization, i.e. the msgsnd() can race ahead until the = =0A= > kernel buffer is full and then a block with msgrcv() follows or it could = =0A= > be pairs of alternating msgsnd()/msgrcv() operations.=0A= > No special features are used: each pair of threads has it's own message = =0A= > queues, all messages have type=3D1.=0A= >=0A= > Vineet ran strace - and just before the signal from killing msgctl08, =0A= > there are only msgsnd()/msgrcv() calls.=0A= > Vineet:=0A= > a) could you run strace tomorrow again, with '-ttt' as an additional =0A= > option? I don't see where exactly it hangs.=0A= =0A= Yet to do this.=0A= =0A= > b) Could you check that it is not just a performance regression?=0A= > Does ./msgctl08 1000 16 hang, too?=0A= =0A= Nope that doesn't hang. The minimal configuration that hangs reliably is ms= gctl=0A= 50000 2=0A= =0A= With this config there are 3 processes.=0A= ...=0A= 555 554 root S 1208 0.4 0 0.0 ./msgctl08 50000 2=0A= 554 551 root S 1208 0.4 0 0.0 ./msgctl08 50000 2=0A= 551 496 root S 1208 0.4 0 0.0 ./msgctl08 50000 2=0A= ...=0A= =0A= [ARCLinux]$ cat /proc/551/stack=0A= [<80aec3c6>] do_wait+0xa02/0xc94=0A= [<80aecad2>] SyS_wait4+0x52/0xa4=0A= [<80ae24fc>] ret_from_system_call+0x0/0x4=0A= =0A= [ARCLinux]$ cat /proc/555/stack=0A= [<80c2950e>] SyS_msgrcv+0x252/0x420=0A= [<80ae24fc>] ret_from_system_call+0x0/0x4=0A= =0A= [ARCLinux]$ cat /proc/554/stack=0A= [<80c28c82>] do_msgsnd+0x116/0x35c=0A= [<80ae24fc>] ret_from_system_call+0x0/0x4=0A= =0A= Is this a case of lost wakeup or some such. I'm running with some more diag= nostics=0A= and will report soon ...=0A= =0A= -Vineet=0A= -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org