From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <461D6413.6050605@cosmosbay.com> Date: Thu, 12 Apr 2007 00:41:23 +0200 From: Eric Dumazet MIME-Version: 1.0 Subject: Re: [PATCH] make MADV_FREE lazily free memory References: <461C6452.1000706@redhat.com> In-Reply-To: <461C6452.1000706@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org Return-Path: To: Rik van Riel Cc: linux-kernel , linux-mm , Ulrich Drepper List-ID: Rik van Riel a A(C)crit : > Make it possible for applications to have the kernel free memory > lazily. This reduces a repeated free/malloc cycle from freeing > pages and allocating them, to just marking them freeable. If the > application wants to reuse them before the kernel needs the memory, > not even a page fault will happen. > Hi Rik I dont understand this last sentence. If not even a page fault happens, how the kernel knows that the page was eventually reused by the application, and should not be freed in case of memory pressure ? ptr = mmap(some space); madvise(ptr, length, MADV_FREE); /* kernel may free the pages */ sleep(10); /* what the application must do know before reusing space ? */ memset(ptr, data, 10000); /* kernel should not free ptr[0..10000] now */ Thank you -- 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: email@kvack.org