tracing: Simplify the max length test when using the filtering temp buffer

Browse source

When filtering trace events, a temp buffer is used because the extra copy
from the temp buffer into the ring buffer is still faster than the direct
write into the ring buffer followed by a discard if the filter does not
match.

But the data that can be stored in the temp buffer is a PAGE_SIZE minus the
ring buffer event header. The calculation of that header size is complex,
but using the helper macro "struct_size()" can simplify it.

Link: https://lore.kernel.org/stable/CAHk-=whKbJkuVmzb0hD3N6q7veprUrSpiBHRxVY=AffWZPtxmg@mail.gmail.com/

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

...

This commit is contained in:

Steven Rostedt (VMware) 2021-06-09 18:04:58 -04:00

parent 99f4f5d623

commit faa76a6c28

1 changed files with 3 additions and 1 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

4

kernel/trace/trace.c

View file