From c71a896154119f4ca9e89d6078f5f63ad60ef199 Mon Sep 17 00:00:00 2001 From: Arnaldo Carvalho de Melo Date: Fri, 23 Jan 2009 12:06:27 -0200 Subject: blktrace: add ftrace plugin Impact: New way of using the blktrace infrastructure This drops the requirement of userspace utilities to use the blktrace facility. Configuration is done thru sysfs, adding a "trace" directory to the partition directory where blktrace can be enabled for the associated request_queue. The same filters present in the IOCTL interface are present as sysfs device attributes. The /sys/block/sdX/sdXN/trace/enable file allows tracing without any filters. The other files in this directory: pid, act_mask, start_lba and end_lba can be used with the same meaning as with the IOCTL interface. Using the sysfs interface will only setup the request_queue->blk_trace fields, tracing will only take place when the "blk" tracer is selected via the ftrace interface, as in the following example: To see the trace, one can use the /d/tracing/trace file or the /d/tracign/trace_pipe file, with semantics defined in the ftrace documentation in Documentation/ftrace.txt. [root@f10-1 ~]# cat /t/trace kjournald-305 [000] 3046.491224: 8,1 A WBS 6367 + 8 <- (8,1) 6304 kjournald-305 [000] 3046.491227: 8,1 Q R 6367 + 8 [kjournald] kjournald-305 [000] 3046.491236: 8,1 G RB 6367 + 8 [kjournald] kjournald-305 [000] 3046.491239: 8,1 P NS [kjournald] kjournald-305 [000] 3046.491242: 8,1 I RBS 6367 + 8 [kjournald] kjournald-305 [000] 3046.491251: 8,1 D WB 6367 + 8 [kjournald] kjournald-305 [000] 3046.491610: 8,1 U WS [kjournald] 1 -0 [000] 3046.511914: 8,1 C RS 6367 + 8 [6367] [root@f10-1 ~]# The default line context (prefix) format is the one described in the ftrace documentation, with the blktrace specific bits using its existing format, described in blkparse(8). If one wants to have the classic blktrace formatting, this is possible by using: [root@f10-1 ~]# echo blk_classic > /t/trace_options [root@f10-1 ~]# cat /t/trace 8,1 0 3046.491224 305 A WBS 6367 + 8 <- (8,1) 6304 8,1 0 3046.491227 305 Q R 6367 + 8 [kjournald] 8,1 0 3046.491236 305 G RB 6367 + 8 [kjournald] 8,1 0 3046.491239 305 P NS [kjournald] 8,1 0 3046.491242 305 I RBS 6367 + 8 [kjournald] 8,1 0 3046.491251 305 D WB 6367 + 8 [kjournald] 8,1 0 3046.491610 305 U WS [kjournald] 1 8,1 0 3046.511914 0 C RS 6367 + 8 [6367] [root@f10-1 ~]# Using the ftrace standard format allows more flexibility, such as the ability of asking for backtraces via trace_options: [root@f10-1 ~]# echo noblk_classic > /t/trace_options [root@f10-1 ~]# echo stacktrace > /t/trace_options [root@f10-1 ~]# cat /t/trace kjournald-305 [000] 3318.826779: 8,1 A WBS 6375 + 8 <- (8,1) 6312 kjournald-305 [000] 3318.826782: <= submit_bio <= submit_bh <= sync_dirty_buffer <= journal_commit_transaction <= kjournald <= kthread <= child_rip kjournald-305 [000] 3318.826836: 8,1 Q R 6375 + 8 [kjournald] kjournald-305 [000] 3318.826837: <= generic_make_request <= submit_bio <= submit_bh <= sync_dirty_buffer <= journal_commit_transaction <= kjournald <= kthread Please read the ftrace documentation to use aditional, standardized tracing filters such as /d/tracing/trace_cpumask, etc. See also /d/tracing/trace_mark to add comments in the trace stream, that is equivalent to the /d/block/sdaN/msg interface. Signed-off-by: Arnaldo Carvalho de Melo Signed-off-by: Ingo Molnar --- fs/partitions/check.c | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'fs/partitions') diff --git a/fs/partitions/check.c b/fs/partitions/check.c index 6d720243f5f..01714efdc65 100644 --- a/fs/partitions/check.c +++ b/fs/partitions/check.c @@ -268,6 +268,10 @@ ssize_t part_fail_store(struct device *dev, } #endif +#ifdef CONFIG_BLK_DEV_IO_TRACE +extern struct attribute_group blk_trace_attr_group; +#endif + static DEVICE_ATTR(partition, S_IRUGO, part_partition_show, NULL); static DEVICE_ATTR(start, S_IRUGO, part_start_show, NULL); static DEVICE_ATTR(size, S_IRUGO, part_size_show, NULL); @@ -294,6 +298,9 @@ static struct attribute_group part_attr_group = { static struct attribute_group *part_attr_groups[] = { &part_attr_group, +#ifdef CONFIG_BLK_DEV_IO_TRACE + &blk_trace_attr_group, +#endif NULL }; -- cgit v1.2.3 From 157f9c00e88529ed84bd7d581a40d411e5414cf0 Mon Sep 17 00:00:00 2001 From: Arnaldo Carvalho de Melo Date: Mon, 26 Jan 2009 15:00:56 -0200 Subject: tracing/blktrace: fix up checkpatch reported problems in ftrace plugin patch Also make sure sparse (make C=2 block/blktrace.o) is happy too. Reported-by: Ingo Molnar Signed-off-by: Arnaldo Carvalho de Melo Signed-off-by: Ingo Molnar --- fs/partitions/check.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) (limited to 'fs/partitions') diff --git a/fs/partitions/check.c b/fs/partitions/check.c index 01714efdc65..8a17f7edcc7 100644 --- a/fs/partitions/check.c +++ b/fs/partitions/check.c @@ -19,6 +19,7 @@ #include #include #include +#include #include "check.h" @@ -268,10 +269,6 @@ ssize_t part_fail_store(struct device *dev, } #endif -#ifdef CONFIG_BLK_DEV_IO_TRACE -extern struct attribute_group blk_trace_attr_group; -#endif - static DEVICE_ATTR(partition, S_IRUGO, part_partition_show, NULL); static DEVICE_ATTR(start, S_IRUGO, part_start_show, NULL); static DEVICE_ATTR(size, S_IRUGO, part_size_show, NULL); -- cgit v1.2.3