From: Andi Kleen <andi@firstfloor.org> To: "Chris Friesen" <cfriesen@nortel.com> Cc: Ingo Molnar <mingo@elte.hu>, Peter Zijlstra <a.p.zijlstra@chello.nl>, Thomas Gleixner <tglx@linutronix.de>, Steven Rostedt <rostedt@goodmis.org>, David Miller <davem@davemloft.net>, linuxppc-dev@ozlabs.org, paulus@samba.org, netdev@vger.kernel.org Subject: Re: question about softirqs Date: Wed, 13 May 2009 10:34:57 +0200 [thread overview] Message-ID: <874ovpmmdq.fsf@basil.nowhere.org> (raw) In-Reply-To: <4A09933B.8010606@nortel.com> (Chris Friesen's message of "Tue, 12 May 2009 09:18:19 -0600") "Chris Friesen" <cfriesen@nortel.com> writes: > > One of the reasons I brought up this issue is that there is a lot of > documentation out there that says "softirqs will be processed on return > from a syscall". The fact that it actually depends on the scheduler > parameters of the task issuing the syscall isn't ever mentioned. It's not mentioned because it is not currently. However some network TCP RX processing can happen in process context, which gives you most of the benefit anyways. > In fact, "Documentation/DocBook/kernel-hacking.tmpl" in the kernel > source still has the following: > > Whenever a system call is about to return to userspace, or a > hardware interrupt handler exits, any 'software interrupts' > which are marked pending (usually by hardware interrupts) are > run (<filename>kernel/softirq.c</filename>). > > If anyone is looking at changing this code, it might be good to ensure > that at least the kernel docs are updated. So far the code is not changed in mainline. There have been some proposals only. -Andi -- ak@linux.intel.com -- Speaking for myself only.
WARNING: multiple messages have this Message-ID (diff)
From: Andi Kleen <andi@firstfloor.org> To: "Chris Friesen" <cfriesen@nortel.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>, netdev@vger.kernel.org, Steven Rostedt <rostedt@goodmis.org>, David Miller <davem@davemloft.net>, linuxppc-dev@ozlabs.org, paulus@samba.org, Ingo Molnar <mingo@elte.hu>, Thomas Gleixner <tglx@linutronix.de> Subject: Re: question about softirqs Date: Wed, 13 May 2009 10:34:57 +0200 [thread overview] Message-ID: <874ovpmmdq.fsf@basil.nowhere.org> (raw) In-Reply-To: <4A09933B.8010606@nortel.com> (Chris Friesen's message of "Tue, 12 May 2009 09:18:19 -0600") "Chris Friesen" <cfriesen@nortel.com> writes: > > One of the reasons I brought up this issue is that there is a lot of > documentation out there that says "softirqs will be processed on return > from a syscall". The fact that it actually depends on the scheduler > parameters of the task issuing the syscall isn't ever mentioned. It's not mentioned because it is not currently. However some network TCP RX processing can happen in process context, which gives you most of the benefit anyways. > In fact, "Documentation/DocBook/kernel-hacking.tmpl" in the kernel > source still has the following: > > Whenever a system call is about to return to userspace, or a > hardware interrupt handler exits, any 'software interrupts' > which are marked pending (usually by hardware interrupts) are > run (<filename>kernel/softirq.c</filename>). > > If anyone is looking at changing this code, it might be good to ensure > that at least the kernel docs are updated. So far the code is not changed in mainline. There have been some proposals only. -Andi -- ak@linux.intel.com -- Speaking for myself only.
next prev parent reply other threads:[~2009-05-13 8:35 UTC|newest] Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top 2009-05-08 22:51 question about softirqs Chris Friesen 2009-05-08 23:05 ` David Miller 2009-05-08 23:34 ` Paul Mackerras 2009-05-08 23:53 ` David Miller 2009-05-09 2:52 ` Benjamin Herrenschmidt 2009-05-09 3:31 ` Paul Mackerras 2009-05-09 6:48 ` David Miller 2009-05-11 18:25 ` Chris Friesen 2009-05-11 23:24 ` David Miller 2009-05-12 0:43 ` Chris Friesen 2009-05-12 8:12 ` Ingo Molnar 2009-05-12 8:12 ` Ingo Molnar 2009-05-12 9:12 ` Peter Zijlstra 2009-05-12 9:23 ` Ingo Molnar 2009-05-12 9:32 ` Peter Zijlstra 2009-05-12 12:20 ` Steven Rostedt 2009-05-12 12:20 ` Steven Rostedt 2009-05-13 4:45 ` David Miller 2009-05-13 4:44 ` David Miller 2009-05-13 4:44 ` David Miller 2009-05-13 5:15 ` Paul Mackerras 2009-05-13 5:15 ` Paul Mackerras 2009-05-13 5:28 ` David Miller 2009-05-13 5:28 ` David Miller 2009-05-13 5:55 ` Evgeniy Polyakov 2009-05-13 5:55 ` Evgeniy Polyakov 2009-05-12 15:18 ` Chris Friesen 2009-05-12 15:18 ` Chris Friesen 2009-05-13 8:34 ` Andi Kleen [this message] 2009-05-13 8:34 ` Andi Kleen 2009-05-13 13:23 ` Chris Friesen 2009-05-13 14:15 ` Andi Kleen 2009-05-13 14:15 ` Andi Kleen 2009-05-13 14:17 ` Thomas Gleixner 2009-05-13 14:17 ` Thomas Gleixner 2009-05-13 14:24 ` Andi Kleen 2009-05-13 14:24 ` Andi Kleen 2009-05-13 14:54 ` Eric Dumazet 2009-05-13 14:54 ` Eric Dumazet 2009-05-13 15:02 ` Andi Kleen 2009-05-13 15:02 ` Andi Kleen 2009-05-13 15:05 ` Chris Friesen 2009-05-13 15:54 ` Thomas Gleixner 2009-05-13 15:54 ` Thomas Gleixner 2009-05-13 16:10 ` Chris Friesen 2009-05-13 17:01 ` Andi Kleen 2009-05-13 19:04 ` Chris Friesen 2009-05-13 19:04 ` Chris Friesen 2009-05-13 19:13 ` Andi Kleen 2009-05-13 19:13 ` Andi Kleen 2009-05-13 19:44 ` Chris Friesen 2009-05-13 19:53 ` Andi Kleen 2009-05-13 19:53 ` Andi Kleen 2009-05-13 20:55 ` Thomas Gleixner 2009-05-13 20:55 ` Thomas Gleixner 2009-05-11 23:34 ` Paul Mackerras 2009-05-09 0:28 ` Chris Friesen
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