Signed-off-by: Steffen Maier <maier@xxxxxxxxxxxxx> --- doc/blkparse.1 | 8 ++++++-- doc/blktrace.tex | 19 ++++++++++++++----- 2 files changed, 20 insertions(+), 7 deletions(-) diff --git a/doc/blkparse.1 b/doc/blkparse.1 index cedd08e2dc5b..d334d25dac15 100644 --- a/doc/blkparse.1 +++ b/doc/blkparse.1 @@ -293,9 +293,13 @@ driver. This may happen automatically if a timeout period has passed (see next entry) or if a number of requests have been added to the queue. .HP 4 -\fBT -- unplug due to timer\fR +\fBT -- unplug due to timer / schedule\fR If nobody requests the i/o that was queued after plugging the queue, Linux will automatically unplug it after a defined period has passed. +Since kernel 2.6.39 and the new on-stack plugging, the equivalent is +an unplug due to process scheduling +.\" https://lwn.net/Articles/438256/ +.\" v2.6.39 commit 49cac01e1fa7 ("block: make unplug timer trace event correspond to the schedule() unplug") .HP 4 \fBX -- split\fR @@ -535,7 +539,7 @@ square brackets) is output. \fBU \-\- unplug\fR .br -\fBT \-\- unplug due to timer\fR +\fBT \-\- unplug due to timer / schedule\fR .RS 4 The command associated with the event (surrounded by square brackets) is output, followed by the number of diff --git a/doc/blktrace.tex b/doc/blktrace.tex index 06de4be1a64b..539362f657d4 100644 --- a/doc/blktrace.tex +++ b/doc/blktrace.tex @@ -602,9 +602,13 @@ Short & Long & Description \\ \hline\hline if a timeout period has passed (see next entry) or if a number of requests have been added to the queue. - \item[T -- unplug due to timer] If nobody requests the io that was queued + \item[T -- unplug due to timer / schedule] If nobody requests the io that was queued after plugging the queue, Linux will automatically unplug it after a - defined period has passed. + defined period has passed. Since kernel 2.6.39 and the new on-stack plugging, + the equivalent is an unplug due to process scheduling\footnote{ + \url{https://lwn.net/Articles/438256/}\newline + v2.6.39 commit 49cac01e1fa7 (``block: make unplug timer trace + event correspond to the schedule() unplug'') }. \item[X -- split] On raid or device mapper setups, an incoming io may straddle a device or internal zone and needs to be chopped up into @@ -702,7 +706,7 @@ P & Plug request \\ \hline Q & IO handled by request queue code \\ \hline R & Requeued \\ \hline S & Sleep request \\ \hline -T & Unplug due to timeout \\ \hline +T & Unplug due to timeout / schedule \\ \hline U & Unplug request \\ \hline X & Split \\ \hline \end{tabular} @@ -794,7 +798,7 @@ default output ends each event with a newline character square brackets) is output. \item[U -- unplug] - \item[T -- unplug due to timer] The command associated with the event + \item[T -- unplug due to timer / schedule] The command associated with the event (surrounded by square brackets) is output, followed by the number of requests outstanding. @@ -841,13 +845,18 @@ definitions: BLK\_TA\_COMPLETE & Command completed by driver. \\ \hline BLK\_TA\_PLUG & Device is plugged \\ \hline BLK\_TA\_UNPLUG\_IO & Unplug device as IO is made available. \\ \hline - BLK\_TA\_UNPLUG\_TIMER & Unplug device after timer expired. \\ \hline + BLK\_TA\_UNPLUG\_TIMER & Unplug device after timer expired + / process schedule\footnotemark[42]. \\ \hline BLK\_TA\_INSERT & Insert request into queue. \\ \hline BLK\_TA\_SPLIT & BIO split into 2 or more requests. \\ \hline BLK\_TA\_BOUNCE & BIO was bounced \\ \hline BLK\_TA\_REMAP & BIO was remapped \\ \hline \end{tabular} +\footnotetext[42]{\url{https://lwn.net/Articles/438256/}\newline + v2.6.39 commit 49cac01e1fa7 (``block: make unplug timer trace + event correspond to the schedule() unplug'') } + %.......................................... \subsection{blktrace.h Routines} Files which include $<linux/blktrace.h>$ are supplied with the following -- 2.14.2 -- To unsubscribe from this list: send the line "unsubscribe linux-btrace" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
