On Thu, Nov 20, 2008 at 11:17 PM, ruby <ruby185@xxxxxxxxx> wrote:
> Thanks for the reply and effort of trying this out.
> would you mind spelling out the full ftrace command you used?
>
depends on what u want....i think it is better for u to fully
understand the usage and meaning of this new technique.....just read
Documentation/ftrace.txt.
And for my script:
#!/bin/bash
mkdir /debug
mount -t debugfs nodev /debug
echo 0 >/debug/tracing/tracing_enabled
echo 'ext3_*' 'journal_*' > /debug/tracing/set_ftrace_filter
echo function >/debug/tracing/current_tracer
echo 1 >/debug/tracing/tracing_enabled
gedit /var/log/messages &
sleep 3
echo 0 >/debug/tracing/tracing_enabled
cat /debug/tracing/trace
And the eliminating all those non "gedit" lines from the output we can
see the flow kernel APIs being called.....for the above it is:
gedit-4138 [001] 375.163088: ext3_permission <-inode_permission
gedit-4138 [001] 375.163088: ext3_permission <-inode_permission
gedit-4138 [001] 375.163101: ext3_dirty_inode <-__mark_inode_dirty
gedit-4138 [001] 375.163101: ext3_journal_start_sb
<-ext3_dirty_inode
gedit-4138 [001] 375.163101: journal_start <-ext3_journal_start_sb
gedit-4138 [001] 375.163103: ext3_mark_inode_dirty
<-ext3_dirty_inode
gedit-4138 [001] 375.163103: ext3_reserve_inode_write
<-ext3_mark_inode_dirty
gedit-4138 [001] 375.163103: ext3_get_inode_loc
<-ext3_reserve_inode_write
gedit-4138 [001] 375.163104: ext3_get_group_desc
<-__ext3_get_inode_loc
gedit-4138 [001] 375.163107: journal_get_write_access
<-__ext3_journal_get_write_access
gedit-4138 [001] 375.163107: journal_add_journal_head
<-journal_get_write_access
gedit-4138 [001] 375.163110: journal_cancel_revoke
<-do_get_write_access
gedit-4138 [001] 375.163110: journal_put_journal_head
<-journal_get_write_access
gedit-4138 [001] 375.163110: ext3_mark_iloc_dirty
<-ext3_mark_inode_dirty
gedit-4138 [001] 375.163111: ext3_get_inode_flags
<-ext3_mark_iloc_dirty
gedit-4138 [001] 375.163111: journal_dirty_metadata
<-__ext3_journal_dirty_metadata
gedit-4138 [001] 375.163112: journal_stop <-__ext3_journal_stop
gedit-4138 [001] 375.163141: ext3_permission <-inode_permission
gedit-4138 [001] 375.163142: ext3_permission <-inode_permission
>From the above we can see how the ext3 filesystem uses the journal_*
API to record its journal, caller-callee APIs relationship etc. If
every line we can see a stacktrace, more information can be revealed.
Thanks.
--
Regards,
Peter Teoh
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