On Wed, Oct 27, 2021 at 7:58 PM Kalesh Singh kaleshsingh@google.com wrote:
On Wed, Oct 27, 2021 at 5:43 PM Masami Hiramatsu mhiramat@kernel.org wrote:
On Wed, 27 Oct 2021 19:54:54 -0400 Steven Rostedt rostedt@goodmis.org wrote:
On Wed, 27 Oct 2021 16:26:00 -0700 Kalesh Singh kaleshsingh@google.com wrote:
Why don't you use 'tac'? I love that idea :) Did you find any issue?
Hi Masami,
Thanks for the reviews. As with the first set of patches using tac gives a regression here, though I'm not sure why it doesn't work -- I also thought reversing the order would handle any dependencies correctly.
Right, because are triggers not added by list_add_rcu() which adds to the head of the list.
Oops, so are the triggers shown in the reverse order? (newer entry is top, older one is bottom) Then do we need this patch, because we don't care about the dependency.
In the case of the hist expression tests. they create a variable: echo 'hist:keys=common_pid:x=1+2' >> trigger
Then print its value in another histogram: echo 'hist:keys=common_pid:vals=$x' >> trigger
At least in this case, the triggers are listed from oldest (top) to newest (bottom): cat trigger hist:keys=common_pid:vals=hitcount:x=3:sort=hitcount:size=2048 [active]
I realized the result of the expression can be read directly from the trigger info, now that expressions of constants are squashed to a single constant. So we wouldn't need the second trigger to see the value and can drop this patch. I'll resend a new version.
Thanks, Kalesh
hist:keys=common_pid:vals=hitcount,$x:sort=hitcount:size=2048 [active]
So we need to remove the trigger with the var ref first.
- Kalesh
If anything, shouldn't things be removed in order?
Hmm, I think the trigger itself might better to be changed. If any dependency in the trigger list, it can not be restored from the copied file, like below may fail.
cat events/foo/bar/trigger > /tmp/foo.bar.trigger cat /tmp/foo.bar.trigger > events/foo/bar/trigger
(of course we can use 'tac' to restore it ...)
This is
Thank you,
-- Masami Hiramatsu mhiramat@kernel.org