From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f174.google.com (mail-wi0-f174.google.com [209.85.212.174]) by kanga.kvack.org (Postfix) with ESMTP id 4CB5A6B0032 for ; Thu, 11 Jun 2015 11:48:33 -0400 (EDT) Received: by wifx6 with SMTP id x6so12856457wif.0 for ; Thu, 11 Jun 2015 08:48:32 -0700 (PDT) Received: from mail-wi0-x244.google.com (mail-wi0-x244.google.com. [2a00:1450:400c:c05::244]) by mx.google.com with ESMTPS id ym6si1951110wjc.130.2015.06.11.08.48.31 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 11 Jun 2015 08:48:31 -0700 (PDT) Received: by wibbw19 with SMTP id bw19so4043106wib.2 for ; Thu, 11 Jun 2015 08:48:31 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: From: Timofey Titovets Date: Thu, 11 Jun 2015 18:47:50 +0300 Message-ID: Subject: Fwd: Why rapiddisk cache, better then build-in ram cache? Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org List-ID: To: linux-mm@kvack.org Hello list, I'm very sorry, what i've forward mail it to linux-mm list, but i can't find any mailing list like linux-block-io or something like that %) I've recently find rapid cache and it confuse me, as i know, linux use almost all free ram for IO caching and do it very cool and fast. May be i misstake in something? May be linux memory io cache sub system not fast as i think? ---------- Forwarded message ---------- From: Petros Koutoupis Date: 2015-06-11 18:33 GMT+03:00 Subject: Re: Why rapiddisk cache, better then build-in ram cache? To: Timofey Titovets =D0=9A=D0=BE=D0=BF=D0=B8=D1=8F: support@inverness-data.com Timofey, Thank you very much for you interest in the project. Linux does not have a built block I/O cache. All block I/O resides in a temporary buffer until the schedular schedules the task to the block device; that is, unless you are running Direct I/O in which all I/O is immediately dispatched regardless of the schedular. Now a file system will cache data in the VFS layer but this cache is somewhat small and limited. With RapidDisk / RapidCache, you can easily enable 1GB or even 1TB of cache to a slower block device, thus enabling a block based cache. Or you can simply just enable a large RAM based block device and not use it as a cache. I guess it all depends on your requirements. You are correct, though. This should be detailed on the Wiki and I will definitely address it. Thank you for bringing it to our attention. On Thu, Jun 11, 2015 at 10:26 AM, Timofey Titovets w= rote: > > Hello, > i've read http://rapiddisk.org/index.php?title=3DMain_Page > That a very cool, > but i can't understand why it better than linux built in file/block io ca= che? > > May be you can explain it on wiki page? > > -- > Have a nice day, > Timofey. -- Petros Koutoupis Inverness Storage Solutions, LLC 312-854-9707 pkoutoupis@inverness-data.com --=20 Have a nice day, Timofey. -- 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