From mboxrd@z Thu Jan 1 00:00:00 1970 From: ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org (Eric W. Biederman) Subject: Re: [PATCH] pid: improved namespaced iteration over processes list Date: Mon, 15 Dec 2008 13:50:55 -0800 Message-ID: References: <1229359793-4029-1-git-send-email-gomuthuk@linux.vnet.ibm.com> <1229365974.17206.190.camel@nimitz> <20081215194603.GA11958@us.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20081215194603.GA11958-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org> (Sukadev Bhattiprolu's message of "Mon, 15 Dec 2008 11:46:03 -0800") List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Sukadev Bhattiprolu Cc: containers , Balbir , Dave Hansen List-Id: containers.vger.kernel.org Sukadev Bhattiprolu writes: > The obvious trade-off is with systems that don't use containers which > are porbably the majority at present. For them next_task() now becomes > more expensive (instead of a simply going to next item on list, they have > lookup in the pidmap, a lookup in pid hash table followed by mapping the > pid back to task). I think there was a discussion once on this and the > conclusion was things like "kill sig -1" are inherently expensive. Cost wise it would be worth measuring. I have a report that when that change was made to /proc readdir in /proc sped up. The problem that I see is that changing generic methods is not generally applicable. > Do you need these to be optimized for containers for some other reason ? A good question. Eric