From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx111.postini.com [74.125.245.111]) by kanga.kvack.org (Postfix) with SMTP id 571206B0031 for ; Mon, 5 Aug 2013 14:04:26 -0400 (EDT) Received: by mail-ob0-f175.google.com with SMTP id xn12so6106920obc.6 for ; Mon, 05 Aug 2013 11:04:25 -0700 (PDT) MIME-Version: 1.0 Date: Mon, 5 Aug 2013 11:04:25 -0700 Message-ID: Subject: swap behavior during fast allocation From: Luigi Semenzato Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: linux-mm@kvack.org Greetings MM experts, we (Chrome OS) are experiencing episodes of extremely sluggish interactive response, i.e. tens of seconds delay between an action (such as typing something) and the corresponding screen update during times of very fast allocation, while using zram. We can reproduce this by running a few processes that mmap large chunks of memory, then randomly touch pages to fault them in. We also think this happens when a process writes a large amount of data using buffered I/O, and the "Buffers" field in /proc/meminfo exceeds 1GB. (This is something that can and should be corrected by using unbuffered I/O instead, but it's a data point.) We're wondering if this problem has been noticed before and what folks do to ameliorate the situation. Specifically, is there any way to throttle the rate of allocation when the system is swapping? Thanks! Luigi -- 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