From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f198.google.com (mail-wr0-f198.google.com [209.85.128.198]) by kanga.kvack.org (Postfix) with ESMTP id 6661B6B0003 for ; Tue, 6 Mar 2018 19:23:50 -0500 (EST) Received: by mail-wr0-f198.google.com with SMTP id u36so255609wrf.21 for ; Tue, 06 Mar 2018 16:23:50 -0800 (PST) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org. [140.211.169.12]) by mx.google.com with ESMTPS id g132si1369850wmd.211.2018.03.06.16.23.48 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 06 Mar 2018 16:23:49 -0800 (PST) Date: Tue, 6 Mar 2018 16:23:46 -0800 From: Andrew Morton Subject: Re: [Bug 198913] New: Swapping slows to about 20% of expected speed when using multiple swap partitions on separate drives (striping). Message-Id: <20180306162346.2fad560fa6957480fde918e2@linux-foundation.org> In-Reply-To: References: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: dan@daniel-wynne-humphries.com Cc: bugzilla-daemon@bugzilla.kernel.org, linux-mm@kvack.org, Hugh Dickins (switched to email. Please respond via emailed reply-to-all, not via the bugzilla web interface). On Sat, 24 Feb 2018 03:56:38 +0000 bugzilla-daemon@bugzilla.kernel.org wrote: > https://bugzilla.kernel.org/show_bug.cgi?id=198913 > > Bug ID: 198913 > Summary: Swapping slows to about 20% of expected speed when > using multiple swap partitions on separate drives > (striping). > > ... > > Problems > 1) Linux's swap striping on nine drives performs at only 19.5% of the speed of > a memory-mapped file on a RAID 0 partition on the same nine drives. > 2) Linux's swap striping performs best with exactly four swap partitions and > performs almost as well with just three partitions. > Well that's interesting, thanks. Let's get this onto the mm developers' mailing list and perhaps someone will have a theory. And perhaps Hugh will have a think about it when he returns to the fold. -- 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