From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Chen, Kenneth W" Date: Mon, 28 Feb 2005 20:07:46 +0000 Subject: RE: [Patch 3/3] Shrink page table quicklist based on free memory. Message-Id: <200502282007.j1SK7ig13891@unix-os.sc.intel.com> List-Id: References: <20050226142716.GG10965@lnx-holt.americas.sgi.com> In-Reply-To: <20050226142716.GG10965@lnx-holt.americas.sgi.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org Robin Holt wrote on Saturday, February 26, 2005 6:27 AM > This patch shrinks the quicklist based upon free memory on the node > instead of the high/low water marks. I also limit the rate of drain from > the quicklist by 256 entries per pass. The limit was placed because this > freeing is done with the preemption disabled and large frees have caused > unexpected bubbles in latency. The 256 was chosen based on some test > runs which showed blips above the noise range with 4096 pages and that 256 > pages resulted in the least amount of overshoot as processes were exiting. > Typical response at 128 would be periodic freeing of pages followed by > allocating at next startup. With 256, this was nearly never observed. I'm not a huge fan of hooking memory free function in idle loop. It's a broken model. They enlarge wake up latency, pollutes caches, slows the system down. Why can't this be done on demand under memory pressure? - Ken