From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <42BB3EFC.7060800@engr.sgi.com> Date: Thu, 23 Jun 2005 18:00:12 -0500 From: Ray Bryant MIME-Version: 1.0 Subject: Re: [PATCH 2.6.12-rc5 0/10] mm: manual page migration-rc3 -- overview References: <20050622163908.25515.49944.65860@tomahawk.engr.sgi.com> In-Reply-To: Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Christoph Lameter Cc: Ray Bryant , Hirokazu Takahashi , Andi Kleen , Dave Hansen , Marcelo Tosatti , Christoph Hellwig , Ray Bryant , linux-mm , lhms-devel@lists.sourceforge.net, Paul Jackson , Nathan Scott List-ID: Christoph Lameter wrote: > On Wed, 22 Jun 2005, Ray Bryant wrote: > > >>(1) This version of migrate_pages() works reliably only when the >> process to be migrated has been stopped (e. g., using SIGSTOP) >> before the migrate_pages() system call is executed. >> (The system doesn't crash or oops, but sometimes the process >> being migrated will be "Killed by VM" when it starts up again. >> There may be a few messages put into the log as well at that time.) >> >> At the moment, I am proposing that processes need to be >> suspended before being migrated. This really should not >> be a performance conern, since the delay imposed by page >> migration far exceeds any delay imposed by SIGSTOPing the >> processes before migration and SIGCONTinuing them afterward. > > > There is PF_FREEZE flag used by the suspend feature that could > be used here to send the process into the "freezer" first. Using regular > signals to stop a process may cause races with user space code also doing > SIGSTOP SIGCONT on a process while migrating it. > > Christoph, So are you suggesting that I set PF_FREEZE, wait until PF_FROZEN is set as well, then migrate the pages, and then clear PF_FROZEN to resume the task? I guess that might work, unless we're actually running on a laptop and it goes into hibernation at the same time we are trying to do a migration.... -- Best Regards, Ray ----------------------------------------------- Ray Bryant 512-453-9679 (work) 512-507-7807 (cell) raybry@sgi.com raybry@austin.rr.com The box said: "Requires Windows 98 or better", so I installed Linux. ----------------------------------------------- -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: aart@kvack.org