From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org ([63.228.1.57]:50149 "EHLO gate.crashing.org") by vger.kernel.org with ESMTP id S268385AbUHKXgE (ORCPT ); Wed, 11 Aug 2004 19:36:04 -0400 Subject: Re: clear_user_highpage() From: Benjamin Herrenschmidt In-Reply-To: <20040811161537.5e24c2b6.davem@redhat.com> References: <20040811161537.5e24c2b6.davem@redhat.com> Content-Type: text/plain Message-Id: <1092267062.2166.19.camel@gaston> Mime-Version: 1.0 Date: Thu, 12 Aug 2004 09:31:03 +1000 Content-Transfer-Encoding: 7bit To: "David S. Miller" Cc: Linus Torvalds , Linux Arch list List-ID: > There is a lot of code path in there for alloc_pages_vma(). > I don't think adding arch overridable stuff is the way > to go here. Something generic in the per-cpu hot/cold > page list handling that the cpu_idle() loop of each architecture > could call. It would be nice, indeed, tho we have to be careful not to waste too much time in there looking for pages to clear, especially when there is none. Time spent not putting the CPU into power managed idle, at least on PPC's, means the CPU getting hotter, consuming more battery, etc... which is definitely a bad thing on laptops. I already took a significant hit with HZ=1000 btw, I'm considering lowering it back to 100 on ppc32 at least... We really want tickless scheduling for these beasts so we can select how deep to PM the CPU based on how much time we expect to stay idle. Ben.