From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Martin J. Bligh" Date: Sun, 07 Nov 2004 16:11:24 +0000 Subject: Re: removing mm->rss and mm->anon_rss from kernel? Message-Id: <226170000.1099843883@[10.10.2.4]> List-Id: References: <4189EC67.40601@yahoo.com.au> <418AD329.3000609@yahoo.com.au> <418AE0F0.5050908@yahoo.com.au> <418AE9BB.1000602@yahoo.com.au><1099622957.29587.101.camel@gaston><418C55A7.9030100@yahoo.com.au> <204290000.1099754257@[10.10.2.4]> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Christoph Lameter Cc: Nick Piggin , Benjamin Herrenschmidt , Hugh Dickins , linux-mm@kvack.org, linux-ia64@vger.kernel.org >> I would've thought SGI would be more worried about this kind of thing >> than anyone else ... what's going to happen when you type 'ps' on a large >> box, and it does this for 10,000 processes? > > Yes but I think this is preferable because of the generally faster > operations of the vm without having to continually update statistics. And > these statistics seem to be quite difficult to properly generate (why else > introduce anon_rss). Without the counters other optimizations are easier > to do. > > Doing a ps is not a frequent event. Of course this may cause > significant load if one does regularly access /proc entities then. Are > there any threads from the past with some numbers of what the impact was > when we calculated rss via proc? Doing ps or top is not unusual at all, and the sysadmins should be able to monitor their system in a reasonable way without crippling it, or even effecting it significantly. >> If you want to make it quicker, how about doing per-cpu stats, and totalling >> them at runtime, which'd be lockless, instead of all the atomic ops? > > That has its own complications and would require lots of memory with > systems that already have up to 10k cpus. Ummm 10K cpus? I hope that's a typo for processes, or this discussion is getting rather silly .... M.