From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail191.messagelabs.com (mail191.messagelabs.com [216.82.242.19]) by kanga.kvack.org (Postfix) with SMTP id 5C49C6B02B9 for ; Mon, 9 Aug 2010 14:32:12 -0400 (EDT) Received: by gwj16 with SMTP id 16so4568592gwj.14 for ; Mon, 09 Aug 2010 11:32:11 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <1281374816-904-8-git-send-email-ngupta@vflare.org> References: <1281374816-904-1-git-send-email-ngupta@vflare.org> <1281374816-904-8-git-send-email-ngupta@vflare.org> Date: Mon, 9 Aug 2010 21:32:11 +0300 Message-ID: Subject: Re: [PATCH 07/10] Increase compressed page size threshold From: Pekka Enberg Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org To: Nitin Gupta Cc: Pekka Enberg , Minchan Kim , Andrew Morton , Greg KH , Linux Driver Project , linux-mm , linux-kernel List-ID: Hi Nitin, On Mon, Aug 9, 2010 at 8:26 PM, Nitin Gupta wrote: > Compression takes much more time than decompression. So, its quite > wasteful in terms of both CPU cycles and memory usage to have a very > low compressed page size threshold and thereby storing such not-so-well > compressible pages as-is (uncompressed). So, increasing it from > PAGE_SIZE/2 to PAGE_SIZE/8*7. A low threshold was useful when we had > "backing swap" support where we could forward such pages to the backing > device (applicable only when zram was used as swap disk). > > It is not yet configurable through sysfs but may be exported in future, > along with threshold for average compression ratio. > > Signed-off-by: Nitin Gupta The description makes sense but lacks any real data. What kind of workloads did you test this with? Where does it help most? How much? Pekka -- 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