From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mathieu Desnoyers Subject: Re: LTTng 0.193 fixes RT kernel support Date: Tue, 23 Feb 2010 07:30:16 -0500 Message-ID: <20100223123016.GA12857@Krystal> References: <1266337450.24271.140.camel@gandalf.stny.rr.com> <20100216164744.GA25115@Krystal> <20100216170540.GA28039@Krystal> <20100217230854.GA25636@Krystal> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Cc: linux-rt-users@vger.kernel.org, linux-kernel@vger.kernel.org, Steven Rostedt , ltt-dev@lists.casi.polymtl.ca, Thomas Gleixner , Ingo Molnar To: naresh kamboju Return-path: Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: ltt-dev-bounces@lists.casi.polymtl.ca List-Id: linux-rt-users.vger.kernel.org * naresh kamboju (naresh.kernel@gmail.com) wrote: > On Mon, Feb 22, 2010 at 9:07 PM, naresh kamboju = wrote: > > On Thu, Feb 18, 2010 at 4:38 AM, Mathieu Desnoyers > > wrote: > >> * naresh kamboju (naresh.kernel@gmail.com) wrote: > >>> Hi, > >>> > >>> On Tue, Feb 16, 2010 at 10:35 PM, Mathieu Desnoyers wrote: > >> [...] > >>> > Oh, right. Thanks for the explanation. I'll look into moving LTTng = to a > >>> > saner del_timer_sync() scheme to delete the timers. > >>> > >>> Could you give more info regarding, what kind of changes we can work = on. > >>> let me also work around on it. > >>> > >> > >> I just released LTTng 0.193 for kernel 2.6.32.4 which includes patches > >> fixing these odd per-cpu timer teardowns. > > > > I have downloaded LTTng 0.193 patches and viewed i can see below patches > > > > 1. lttng-transport-lockless-add-timer-on-works-with-del-timer-sync.patch > > 2. omap-trace-clock-use-del-timer-sync.patch > > 3. x86-trace-clock-use-mod-timer.patch > > 4. trace-clock-32-to-64-use-del-timer-sync.patch > = > FYI. > = > I have ported LTTng 0.193 these four patches and able to resolve the > issues on Uni-processor (UP) on ARM arch Thank you. > = > A different bug is reported on SMP. > = > BUG: using smp_processor_id() in preemptible [00000000] code: lttctl/754 > caller is put_synthetic_tsc+0x7c/0xf8 > = > Backtrace: > [] (dump_backtrace+0x0/0x10c) from [] (dump_stack+0x1= 8/0x1c) > r7:c04c4994 r6:c008e24c r5:00000003 r4:ce0b6000 > [] (dump_stack+0x0/0x1c) from [] > (debug_smp_processor_id+0xc0/0xec) > [] (debug_smp_processor_id+0x0/0xec) from [] > (put_synthetic_tsc+0x7c/0xf8) > r6:c04f82cc r5:c0023600 r4:00000003 > [] (put_synthetic_tsc+0x0/0xf8) from [] > (put_trace_clock+0x68/0x7c) > r8:bece6eb9 r7:0000000b r6:ce0b7d2a r5:cc037600 r4:00000000 > [] (put_trace_clock+0x0/0x7c) from [] > (ltt_trace_destroy+0x40/0x94) > [] (ltt_trace_destroy+0x0/0x94) from [] > (destroy_trace_write+0xbc/0x140) > r5:00000000 r4:0000000b > [] (destroy_trace_write+0x0/0x140) from [] > (vfs_write+0xb4/0x144) > r7:0000000b r6:ce0b7f70 r5:bece6eb9 r4:ceae7860 > [] (vfs_write+0x0/0x144) from [] (sys_write+0x48/0xf4) > r7:0000000b r6:ceae7860 r5:00000000 r4:00000000 > [] (sys_write+0x0/0xf4) from [] > (__sys_trace_return+0x0/0x24) > = > = > patch trace-clock-32-to-64-use-del-timer-sync.patch is causing above > problem on SMP. > = > with out this patch on SMP reported the previous bug as BUG: sleeping > function called from invalid context at kernel/rtmutex.c:685 > = > However, i'll investigate. Hrm, we should turn the arch/{arm/mach-omap2,x86/kernel}/trace-clock.c: trace_clock_lock into a mutex, and kernel/trace/trace-clock-32-to-64.c: synthetic_tsc_lock into a mutex too. I used a spinlock previously on ARM because it was called from power management resume, but now that the data structures touched by this code path are per-cpu, this lock is not taken there, so it should be OK to turn it into a mutex. Can you try that and tell me if that fixes your issues ? Thanks, Mathieu > = > Best regards, > Naresh Kamboju > >> Thanks, > >> > >> Mathieu > >> > >> -- > >> Mathieu Desnoyers > >> OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F =A0BA06 3F25 A8FE 3B= AE 9A68 > >> > > > = > _______________________________________________ > ltt-dev mailing list > ltt-dev@lists.casi.polymtl.ca > http://lists.casi.polymtl.ca/cgi-bin/mailman/listinfo/ltt-dev > = -- = Mathieu Desnoyers OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68