From: Wu Fengguang <fengguang.wu@intel.com> To: Peter Zijlstra <peterz@infradead.org> Cc: "linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>, Andrew Morton <akpm@linux-foundation.org>, Jan Kara <jack@suse.cz>, Christoph Hellwig <hch@lst.de>, Dave Chinner <david@fromorbit.com>, Greg Thelen <gthelen@google.com>, Minchan Kim <minchan.kim@gmail.com>, Vivek Goyal <vgoyal@redhat.com>, Andrea Righi <arighi@develer.com>, linux-mm <linux-mm@kvack.org>, LKML <linux-kernel@vger.kernel.org> Subject: Re: [PATCH 2/5] writeback: dirty position control Date: Fri, 12 Aug 2011 21:19:54 +0800 [thread overview] Message-ID: <20110812131954.GA17781@localhost> (raw) In-Reply-To: <1312910427.1083.68.camel@twins> On Wed, Aug 10, 2011 at 01:20:27AM +0800, Peter Zijlstra wrote: > On Tue, 2011-08-09 at 12:32 +0200, Peter Zijlstra wrote: > > > origin - dirty > > > pos_ratio = -------------- > > > origin - goal > > > > > which comes from the below [*] control line, so that when (dirty == goal), > > > pos_ratio == 1.0: > > > > OK, so basically you want a linear function for which: > > > > f(goal) = 1 and has a root somewhere > goal. > > > > (that one line is much more informative than all your graphs put > > together, one can start from there and derive your function) > > > > That does indeed get you the above function, now what does it mean? > > So going by: > > write_bw > ref_bw = dirty_ratelimit * pos_ratio * -------- > dirty_bw > > pos_ratio seems to be the feedback on the deviation of the dirty pages > around its setpoint. Yes. > So we adjust the reference bw (or rather ratelimit) > to take account of the shift in output vs input capacity as well as the > shift in dirty pages around its setpoint. However the above function should better be interpreted as write_bw ref_bw = task_ratelimit_in_past_200ms * -------- dirty_bw where task_ratelimit_in_past_200ms ~= dirty_ratelimit * pos_ratio It would be highly confusing if trying to find the direct "logical" relationships between ref_bw and pos_ratio in the above equation. > From that we derive the condition that: > > pos_ratio(setpoint) := 1 Right. > Now in order to create a linear function we need one more condition. We > get one from the fact that once we hit the limit we should hard throttle > our writers. We get that by setting the ratelimit to 0, because, after > all, pause = nr_dirtied / ratelimit would yield inf. in that case. Thus: > > pos_ratio(limit) := 0 > > Using these two conditions we can solve the equations and get your: > > limit - dirty > pos_ratio(dirty) = ---------------- > limit - setpoint > > Now, for some reason you chose not to use limit, but something like > min(limit, 4*thresh) something to do with the slope affecting the rate > of adjustment. This wants a comment someplace. Thanks to your reasoning that lead to the more elegant setpoint - dirty 3 pos_ratio(dirty) := 1 + (----------------) limit - setpoint Thanks, Fengguang
WARNING: multiple messages have this Message-ID (diff)
From: Wu Fengguang <fengguang.wu@intel.com> To: Peter Zijlstra <peterz@infradead.org> Cc: "linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>, Andrew Morton <akpm@linux-foundation.org>, Jan Kara <jack@suse.cz>, Christoph Hellwig <hch@lst.de>, Dave Chinner <david@fromorbit.com>, Greg Thelen <gthelen@google.com>, Minchan Kim <minchan.kim@gmail.com>, Vivek Goyal <vgoyal@redhat.com>, Andrea Righi <arighi@develer.com>, linux-mm <linux-mm@kvack.org>, LKML <linux-kernel@vger.kernel.org> Subject: Re: [PATCH 2/5] writeback: dirty position control Date: Fri, 12 Aug 2011 21:19:54 +0800 [thread overview] Message-ID: <20110812131954.GA17781@localhost> (raw) In-Reply-To: <1312910427.1083.68.camel@twins> On Wed, Aug 10, 2011 at 01:20:27AM +0800, Peter Zijlstra wrote: > On Tue, 2011-08-09 at 12:32 +0200, Peter Zijlstra wrote: > > > origin - dirty > > > pos_ratio = -------------- > > > origin - goal > > > > > which comes from the below [*] control line, so that when (dirty == goal), > > > pos_ratio == 1.0: > > > > OK, so basically you want a linear function for which: > > > > f(goal) = 1 and has a root somewhere > goal. > > > > (that one line is much more informative than all your graphs put > > together, one can start from there and derive your function) > > > > That does indeed get you the above function, now what does it mean? > > So going by: > > write_bw > ref_bw = dirty_ratelimit * pos_ratio * -------- > dirty_bw > > pos_ratio seems to be the feedback on the deviation of the dirty pages > around its setpoint. Yes. > So we adjust the reference bw (or rather ratelimit) > to take account of the shift in output vs input capacity as well as the > shift in dirty pages around its setpoint. However the above function should better be interpreted as write_bw ref_bw = task_ratelimit_in_past_200ms * -------- dirty_bw where task_ratelimit_in_past_200ms ~= dirty_ratelimit * pos_ratio It would be highly confusing if trying to find the direct "logical" relationships between ref_bw and pos_ratio in the above equation. > From that we derive the condition that: > > pos_ratio(setpoint) := 1 Right. > Now in order to create a linear function we need one more condition. We > get one from the fact that once we hit the limit we should hard throttle > our writers. We get that by setting the ratelimit to 0, because, after > all, pause = nr_dirtied / ratelimit would yield inf. in that case. Thus: > > pos_ratio(limit) := 0 > > Using these two conditions we can solve the equations and get your: > > limit - dirty > pos_ratio(dirty) = ---------------- > limit - setpoint > > Now, for some reason you chose not to use limit, but something like > min(limit, 4*thresh) something to do with the slope affecting the rate > of adjustment. This wants a comment someplace. Thanks to your reasoning that lead to the more elegant setpoint - dirty 3 pos_ratio(dirty) := 1 + (----------------) limit - setpoint Thanks, Fengguang -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2011-08-12 13:20 UTC|newest] Thread overview: 305+ messages / expand[flat|nested] mbox.gz Atom feed top 2011-08-06 8:44 [PATCH 0/5] IO-less dirty throttling v8 Wu Fengguang 2011-08-06 8:44 ` Wu Fengguang 2011-08-06 8:44 ` Wu Fengguang 2011-08-06 8:44 ` [PATCH 1/5] writeback: account per-bdi accumulated dirtied pages Wu Fengguang 2011-08-06 8:44 ` Wu Fengguang 2011-08-06 8:44 ` Wu Fengguang 2011-08-06 8:44 ` [PATCH 2/5] writeback: dirty position control Wu Fengguang 2011-08-06 8:44 ` Wu Fengguang 2011-08-06 8:44 ` Wu Fengguang 2011-08-08 13:46 ` Peter Zijlstra 2011-08-08 13:46 ` Peter Zijlstra 2011-08-08 13:46 ` Peter Zijlstra 2011-08-08 14:11 ` Wu Fengguang 2011-08-08 14:11 ` Wu Fengguang 2011-08-08 14:31 ` Peter Zijlstra 2011-08-08 14:31 ` Peter Zijlstra 2011-08-08 14:31 ` Peter Zijlstra 2011-08-08 22:47 ` Wu Fengguang 2011-08-08 22:47 ` Wu Fengguang 2011-08-09 9:31 ` Peter Zijlstra 2011-08-09 9:31 ` Peter Zijlstra 2011-08-09 9:31 ` Peter Zijlstra 2011-08-10 12:28 ` Wu Fengguang 2011-08-10 12:28 ` Wu Fengguang 2011-08-08 14:41 ` Peter Zijlstra 2011-08-08 14:41 ` Peter Zijlstra 2011-08-08 14:41 ` Peter Zijlstra 2011-08-08 23:05 ` Wu Fengguang 2011-08-08 23:05 ` Wu Fengguang 2011-08-09 10:32 ` Peter Zijlstra 2011-08-09 10:32 ` Peter Zijlstra 2011-08-09 10:32 ` Peter Zijlstra 2011-08-09 17:20 ` Peter Zijlstra 2011-08-09 17:20 ` Peter Zijlstra 2011-08-09 17:20 ` Peter Zijlstra 2011-08-10 22:34 ` Jan Kara 2011-08-10 22:34 ` Jan Kara 2011-08-11 2:29 ` Wu Fengguang 2011-08-11 2:29 ` Wu Fengguang 2011-08-11 11:14 ` Jan Kara 2011-08-11 11:14 ` Jan Kara 2011-08-16 8:35 ` Wu Fengguang 2011-08-16 8:35 ` Wu Fengguang 2011-08-12 13:19 ` Wu Fengguang [this message] 2011-08-12 13:19 ` Wu Fengguang 2011-08-10 21:40 ` Vivek Goyal 2011-08-10 21:40 ` Vivek Goyal 2011-08-16 8:55 ` Wu Fengguang 2011-08-16 8:55 ` Wu Fengguang 2011-08-11 22:56 ` Peter Zijlstra 2011-08-11 22:56 ` Peter Zijlstra 2011-08-11 22:56 ` Peter Zijlstra 2011-08-12 2:43 ` Wu Fengguang 2011-08-12 2:43 ` Wu Fengguang 2011-08-12 3:18 ` Wu Fengguang 2011-08-12 5:45 ` Wu Fengguang 2011-08-12 5:45 ` Wu Fengguang 2011-08-12 9:45 ` Peter Zijlstra 2011-08-12 9:45 ` Peter Zijlstra 2011-08-12 9:45 ` Peter Zijlstra 2011-08-12 11:07 ` Wu Fengguang 2011-08-12 11:07 ` Wu Fengguang 2011-08-12 12:17 ` Peter Zijlstra 2011-08-12 12:17 ` Peter Zijlstra 2011-08-12 12:17 ` Peter Zijlstra 2011-08-12 9:47 ` Peter Zijlstra 2011-08-12 9:47 ` Peter Zijlstra 2011-08-12 9:47 ` Peter Zijlstra 2011-08-12 11:11 ` Wu Fengguang 2011-08-12 11:11 ` Wu Fengguang 2011-08-12 12:54 ` Peter Zijlstra 2011-08-12 12:54 ` Peter Zijlstra 2011-08-12 12:54 ` Peter Zijlstra 2011-08-12 12:59 ` Wu Fengguang 2011-08-12 12:59 ` Wu Fengguang 2011-08-12 13:08 ` Peter Zijlstra 2011-08-12 13:08 ` Peter Zijlstra 2011-08-12 13:08 ` Peter Zijlstra 2011-08-12 13:04 ` Peter Zijlstra 2011-08-12 13:04 ` Peter Zijlstra 2011-08-12 13:04 ` Peter Zijlstra 2011-08-12 14:20 ` Wu Fengguang 2011-08-12 14:20 ` Wu Fengguang 2011-08-22 15:38 ` Peter Zijlstra 2011-08-22 15:38 ` Peter Zijlstra 2011-08-22 15:38 ` Peter Zijlstra 2011-08-23 3:40 ` Wu Fengguang 2011-08-23 3:40 ` Wu Fengguang 2011-08-23 10:01 ` Peter Zijlstra 2011-08-23 10:01 ` Peter Zijlstra 2011-08-23 10:01 ` Peter Zijlstra 2011-08-23 14:15 ` Wu Fengguang 2011-08-23 14:15 ` Wu Fengguang 2011-08-23 17:47 ` Vivek Goyal 2011-08-23 17:47 ` Vivek Goyal 2011-08-24 0:12 ` Wu Fengguang 2011-08-24 0:12 ` Wu Fengguang 2011-08-24 16:12 ` Peter Zijlstra 2011-08-24 16:12 ` Peter Zijlstra 2011-08-26 0:18 ` Wu Fengguang 2011-08-26 0:18 ` Wu Fengguang 2011-08-26 9:04 ` Peter Zijlstra 2011-08-26 9:04 ` Peter Zijlstra 2011-08-26 10:04 ` Wu Fengguang 2011-08-26 10:04 ` Wu Fengguang 2011-08-26 10:42 ` Peter Zijlstra 2011-08-26 10:42 ` Peter Zijlstra 2011-08-26 10:52 ` Wu Fengguang 2011-08-26 10:52 ` Wu Fengguang 2011-08-26 11:26 ` Wu Fengguang 2011-08-26 12:11 ` Peter Zijlstra 2011-08-26 12:11 ` Peter Zijlstra 2011-08-26 12:20 ` Wu Fengguang 2011-08-26 12:20 ` Wu Fengguang 2011-08-26 13:13 ` Wu Fengguang 2011-08-26 13:18 ` Peter Zijlstra 2011-08-26 13:18 ` Peter Zijlstra 2011-08-26 13:24 ` Wu Fengguang 2011-08-26 13:24 ` Wu Fengguang 2011-08-24 18:00 ` Vivek Goyal 2011-08-24 18:00 ` Vivek Goyal 2011-08-25 3:19 ` Wu Fengguang 2011-08-25 3:19 ` Wu Fengguang 2011-08-25 22:20 ` Vivek Goyal 2011-08-25 22:20 ` Vivek Goyal 2011-08-26 1:56 ` Wu Fengguang 2011-08-26 1:56 ` Wu Fengguang 2011-08-26 8:56 ` Peter Zijlstra 2011-08-26 8:56 ` Peter Zijlstra 2011-08-26 9:53 ` Wu Fengguang 2011-08-26 9:53 ` Wu Fengguang 2011-08-29 13:12 ` Peter Zijlstra 2011-08-29 13:12 ` Peter Zijlstra 2011-08-29 13:37 ` Wu Fengguang 2011-08-29 13:37 ` Wu Fengguang 2011-09-02 12:16 ` Peter Zijlstra 2011-09-02 12:16 ` Peter Zijlstra 2011-09-06 12:40 ` Peter Zijlstra 2011-09-06 12:40 ` Peter Zijlstra 2011-08-24 15:57 ` Peter Zijlstra 2011-08-24 15:57 ` Peter Zijlstra 2011-08-24 15:57 ` Peter Zijlstra 2011-08-25 5:30 ` Wu Fengguang 2011-08-25 5:30 ` Wu Fengguang 2011-08-23 14:36 ` Vivek Goyal 2011-08-23 14:36 ` Vivek Goyal 2011-08-09 2:08 ` Vivek Goyal 2011-08-09 2:08 ` Vivek Goyal 2011-08-16 8:59 ` Wu Fengguang 2011-08-16 8:59 ` Wu Fengguang 2011-08-06 8:44 ` [PATCH 3/5] writeback: dirty rate control Wu Fengguang 2011-08-06 8:44 ` Wu Fengguang 2011-08-06 8:44 ` Wu Fengguang 2011-08-09 14:54 ` Vivek Goyal 2011-08-09 14:54 ` Vivek Goyal 2011-08-11 3:42 ` Wu Fengguang 2011-08-11 3:42 ` Wu Fengguang 2011-08-09 14:57 ` Peter Zijlstra 2011-08-09 14:57 ` Peter Zijlstra 2011-08-09 14:57 ` Peter Zijlstra 2011-08-10 11:07 ` Wu Fengguang 2011-08-10 11:07 ` Wu Fengguang 2011-08-10 16:17 ` Peter Zijlstra 2011-08-10 16:17 ` Peter Zijlstra 2011-08-10 16:17 ` Peter Zijlstra 2011-08-15 14:08 ` Wu Fengguang 2011-08-15 14:08 ` Wu Fengguang 2011-08-09 15:50 ` Vivek Goyal 2011-08-09 15:50 ` Vivek Goyal 2011-08-09 16:16 ` Peter Zijlstra 2011-08-09 16:16 ` Peter Zijlstra 2011-08-09 16:16 ` Peter Zijlstra 2011-08-09 16:19 ` Peter Zijlstra 2011-08-09 16:19 ` Peter Zijlstra 2011-08-09 16:19 ` Peter Zijlstra 2011-08-10 14:07 ` Wu Fengguang 2011-08-10 14:07 ` Wu Fengguang 2011-08-10 14:00 ` Wu Fengguang 2011-08-10 14:00 ` Wu Fengguang 2011-08-10 17:10 ` Peter Zijlstra 2011-08-10 17:10 ` Peter Zijlstra 2011-08-15 14:11 ` Wu Fengguang 2011-08-15 14:11 ` Wu Fengguang 2011-08-09 16:56 ` Peter Zijlstra 2011-08-09 16:56 ` Peter Zijlstra 2011-08-09 16:56 ` Peter Zijlstra 2011-08-10 14:10 ` Wu Fengguang 2011-08-09 17:02 ` Peter Zijlstra 2011-08-09 17:02 ` Peter Zijlstra 2011-08-09 17:02 ` Peter Zijlstra 2011-08-10 14:15 ` Wu Fengguang 2011-08-10 14:15 ` Wu Fengguang 2011-08-06 8:44 ` [PATCH 4/5] writeback: per task dirty rate limit Wu Fengguang 2011-08-06 8:44 ` Wu Fengguang 2011-08-06 8:44 ` Wu Fengguang 2011-08-06 14:35 ` Andrea Righi 2011-08-06 14:35 ` Andrea Righi 2011-08-07 6:19 ` Wu Fengguang 2011-08-07 6:19 ` Wu Fengguang 2011-08-08 13:47 ` Peter Zijlstra 2011-08-08 13:47 ` Peter Zijlstra 2011-08-08 13:47 ` Peter Zijlstra 2011-08-08 14:21 ` Wu Fengguang 2011-08-08 14:21 ` Wu Fengguang 2011-08-08 23:32 ` Wu Fengguang 2011-08-08 23:32 ` Wu Fengguang 2011-08-08 14:23 ` Wu Fengguang 2011-08-08 14:23 ` Wu Fengguang 2011-08-08 14:26 ` Peter Zijlstra 2011-08-08 14:26 ` Peter Zijlstra 2011-08-08 14:26 ` Peter Zijlstra 2011-08-08 22:38 ` Wu Fengguang 2011-08-08 22:38 ` Wu Fengguang 2011-08-13 16:28 ` Andrea Righi 2011-08-13 16:28 ` Andrea Righi 2011-08-15 14:21 ` Wu Fengguang 2011-08-15 14:26 ` Andrea Righi 2011-08-15 14:26 ` Andrea Righi 2011-08-09 17:46 ` Vivek Goyal 2011-08-09 17:46 ` Vivek Goyal 2011-08-10 3:29 ` Wu Fengguang 2011-08-10 3:29 ` Wu Fengguang 2011-08-10 18:18 ` Vivek Goyal 2011-08-10 18:18 ` Vivek Goyal 2011-08-11 0:55 ` Wu Fengguang 2011-08-11 0:55 ` Wu Fengguang 2011-08-09 18:35 ` Peter Zijlstra 2011-08-09 18:35 ` Peter Zijlstra 2011-08-09 18:35 ` Peter Zijlstra 2011-08-10 3:40 ` Wu Fengguang 2011-08-10 3:40 ` Wu Fengguang 2011-08-10 10:25 ` Peter Zijlstra 2011-08-10 10:25 ` Peter Zijlstra 2011-08-10 10:25 ` Peter Zijlstra 2011-08-10 11:13 ` Wu Fengguang 2011-08-10 11:13 ` Wu Fengguang 2011-08-06 8:44 ` [PATCH 5/5] writeback: IO-less balance_dirty_pages() Wu Fengguang 2011-08-06 8:44 ` Wu Fengguang 2011-08-06 8:44 ` Wu Fengguang 2011-08-06 14:48 ` Andrea Righi 2011-08-06 14:48 ` Andrea Righi 2011-08-06 14:48 ` Andrea Righi 2011-08-07 6:44 ` Wu Fengguang 2011-08-07 6:44 ` Wu Fengguang 2011-08-07 6:44 ` Wu Fengguang 2011-08-06 16:46 ` Andrea Righi 2011-08-06 16:46 ` Andrea Righi 2011-08-07 7:18 ` Wu Fengguang 2011-08-07 9:50 ` Andrea Righi 2011-08-07 9:50 ` Andrea Righi 2011-08-09 18:15 ` Vivek Goyal 2011-08-09 18:15 ` Vivek Goyal 2011-08-09 18:41 ` Peter Zijlstra 2011-08-09 18:41 ` Peter Zijlstra 2011-08-09 18:41 ` Peter Zijlstra 2011-08-10 3:22 ` Wu Fengguang 2011-08-10 3:22 ` Wu Fengguang 2011-08-10 3:26 ` Wu Fengguang 2011-08-10 3:26 ` Wu Fengguang 2011-08-09 19:16 ` Vivek Goyal 2011-08-09 19:16 ` Vivek Goyal 2011-08-10 4:33 ` Wu Fengguang 2011-08-09 2:01 ` [PATCH 0/5] IO-less dirty throttling v8 Vivek Goyal 2011-08-09 2:01 ` Vivek Goyal 2011-08-09 5:55 ` Dave Chinner 2011-08-09 5:55 ` Dave Chinner 2011-08-09 14:04 ` Vivek Goyal 2011-08-09 14:04 ` Vivek Goyal 2011-08-10 7:41 ` Greg Thelen 2011-08-10 7:41 ` Greg Thelen 2011-08-10 7:41 ` Greg Thelen 2011-08-10 18:40 ` Vivek Goyal 2011-08-10 18:40 ` Vivek Goyal 2011-08-10 18:40 ` Vivek Goyal 2011-08-11 3:21 ` Wu Fengguang 2011-08-11 3:21 ` Wu Fengguang 2011-08-11 20:42 ` Vivek Goyal 2011-08-11 20:42 ` Vivek Goyal 2011-08-11 21:00 ` Vivek Goyal 2011-08-11 21:00 ` Vivek Goyal 2011-08-16 2:20 [PATCH 0/5] IO-less dirty throttling v9 Wu Fengguang 2011-08-16 2:20 ` [PATCH 2/5] writeback: dirty position control Wu Fengguang 2011-08-16 2:20 ` Wu Fengguang 2011-08-16 2:20 ` Wu Fengguang 2011-08-16 19:41 ` Jan Kara 2011-08-16 19:41 ` Jan Kara 2011-08-17 13:23 ` Wu Fengguang 2011-08-17 13:49 ` Wu Fengguang 2011-08-17 13:49 ` Wu Fengguang 2011-08-17 20:24 ` Jan Kara 2011-08-17 20:24 ` Jan Kara 2011-08-18 4:18 ` Wu Fengguang 2011-08-18 4:18 ` Wu Fengguang 2011-08-18 4:41 ` Wu Fengguang 2011-08-18 4:41 ` Wu Fengguang 2011-08-18 19:16 ` Jan Kara 2011-08-18 19:16 ` Jan Kara 2011-08-24 3:16 ` Wu Fengguang 2011-08-24 3:16 ` Wu Fengguang 2011-08-19 2:53 ` Vivek Goyal 2011-08-19 2:53 ` Vivek Goyal 2011-08-19 3:25 ` Wu Fengguang 2011-08-19 3:25 ` Wu Fengguang [not found] <CAFdhcLRKvfqBnXCXLwq-Qe1eNAGC-8XJ3BtHpQKzaa3RhHyp6A@mail.gmail.com> 2011-08-17 6:40 ` David Horner 2011-08-17 12:03 ` Jan Kara 2011-08-17 12:35 ` Wu Fengguang
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=20110812131954.GA17781@localhost \ --to=fengguang.wu@intel.com \ --cc=akpm@linux-foundation.org \ --cc=arighi@develer.com \ --cc=david@fromorbit.com \ --cc=gthelen@google.com \ --cc=hch@lst.de \ --cc=jack@suse.cz \ --cc=linux-fsdevel@vger.kernel.org \ --cc=linux-kernel@vger.kernel.org \ --cc=linux-mm@kvack.org \ --cc=minchan.kim@gmail.com \ --cc=peterz@infradead.org \ --cc=vgoyal@redhat.com \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.