From mboxrd@z Thu Jan 1 00:00:00 1970 Received: by py-out-1112.google.com with SMTP id f47so5047074pye.20 for ; Mon, 11 Feb 2008 10:37:11 -0800 (PST) Message-ID: <2f11576a0802111037j4fe75e80l695f5a401ec93a7a@mail.gmail.com> Date: Tue, 12 Feb 2008 03:37:10 +0900 From: "KOSAKI Motohiro" Subject: Re: [sample] mem_notify v6: usage example In-Reply-To: <20080211181526.GC3029@webber.adilger.int> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <2f11576a0802090755n123c9b7dh26e0af6a2fef28af@mail.gmail.com> <2f11576a0802090846t7655e988pb1b712696cad1098@mail.gmail.com> <20080211181526.GC3029@webber.adilger.int> Sender: owner-linux-mm@kvack.org Return-Path: To: Andreas Dilger Cc: Jon Masters , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , Marcelo Tosatti , Daniel Spang , Rik van Riel , Andrew Morton , Alan Cox , "linux-fsdevel@vger.kernel.org" , Pavel Machek , Al Boldi , Zan Lynx List-ID: Hi Andreas, Thank you very good comment. > Having such notification handled by glibc to free up unused malloc (or > any heap allocations) would be very useful, because even if a program > does "free" there is no guarantee the memory is returned to the kernel. Yes, no guarantee. but current glibc-malloc very frequently return memory to kernel. glibc default behavior 1. over 1M memory: return memory just free(3) called. (you can change threshold by MALLOC_MMAP_MAX_ environment) 2. more lower: return memory when exist continuous 128k at heap tail. (you can change threashold by MALLOC_TRIM_THRESHOLD_ environment) if you know very memory consumption by already freed memory situation, please tell me situation detail and consumption memory size. > I think that having a generic reservation framework is too complex, but > hiding the details of /dev/mem_notify from applications is desirable. > A simple wrapper (possibly part of glibc) to return the poll fd, or set > up the signal is enough. Agreed. if large consumption situation exist, I'm behind you. Thanks! -- 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