From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 23 Jun 2005 14:31:15 -0700 (PDT) From: Christoph Lameter Subject: Re: [PATCH 2.6.12-rc5 0/10] mm: manual page migration-rc3 -- overview In-Reply-To: <20050622163908.25515.49944.65860@tomahawk.engr.sgi.com> Message-ID: References: <20050622163908.25515.49944.65860@tomahawk.engr.sgi.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Ray Bryant Cc: 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: 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. -- 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