Stephane Eranian wrote:
Tony,
On Mon, Oct 02, 2006 at 04:13:06PM -0700, Luck, Tony wrote:
When discussing the perfmon patch changes with kernel engineers at Red Hat
it was pointed out that struct task_struct is "*enormous*". Really want to
avoid making task_struct any larger than it already is. Are other changes
possible to mitigate the size increase due to yet another pointer in
task_struct? Is there some way to avoid putting the additional field in the
task_struct?
Anil and Stephane did just free up 128 words in the thread structure on
ia64 (which is concatenated to the task structure) in this change:
http://tinyurl.com/nzngv by moving the PMU save areas out of the thread
structure and into the pfm_context. Is something similar possible for other
archs?
This change is already in the 2.2 code base. The PMU state is saved into
a pfm_context struct. The only thing left in tasks_struct is a pointer
to that structure.
Yes, this change is in the existing perfmon 3.2 kernel support for the 2.6.18
kernel. The comment was about the solitary pointer in the newest perfmon patch
set. Every byte is precious. :)
Are additional space savings possible in the task_struct, so that the net is
that task_struct stays the same size?
-Will
_______________________________________________
perfmon mailing list
[email protected]
http://www.hpl.hp.com/hosted/linux/mail-archives/perfmon/
