From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752825AbdLHGLe (ORCPT ); Fri, 8 Dec 2017 01:11:34 -0500 Received: from mail-pg0-f65.google.com ([74.125.83.65]:44561 "EHLO mail-pg0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752627AbdLHGLa (ORCPT ); Fri, 8 Dec 2017 01:11:30 -0500 X-Google-Smtp-Source: AGs4zMYxJx/JLfGWGxoWZMh9OG4Ls0/+dyEI1pka0DvBEgk5MlE7mD9wBV7DAUfiR348qjUOQLA3vw== Date: Fri, 8 Dec 2017 15:11:25 +0900 From: Sergey Senozhatsky To: Sergey Senozhatsky Cc: Gopi Sai Teja , minchan@kernel.org, ngupta@vflare.org, linux-kernel@vger.kernel.org, v.narang@samsung.com, pankaj.m@samsung.com, a.sahrawat@samsung.com, prakash.a@samsung.com, himanshu.sh@samsung.com Subject: Re: [PATCH 1/1] zram: better utilization of zram swap space Message-ID: <20171208061125.GD628@jagdpanzerIV> References: <1512634963-1079-1-git-send-email-gopi.st@samsung.com> <20171207084510.GA10341@jagdpanzerIV> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20171207084510.GA10341@jagdpanzerIV> User-Agent: Mutt/1.9.1 (2017-09-22) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On (12/07/17 17:45), Sergey Senozhatsky wrote: [..] > On (12/07/17 13:52), Gopi Sai Teja wrote: > > If the length of the compressed page is greater than 75% of the PAGE_SIZE, > > then the page is stored uncompressed in zram space. Zram space utilization > > is improved if the threshold is 80%(5 compressed pages can be stored in > > 4 pages). > > > > If the compressed length is greater than 3068 and less than 3261, pages > > still can be stored in compressed form in zs_malloc class 3264. > > Currently these compressed pages belong to 4096 zs malloc class. > > so this makes sense. I had another idea awhile ago > > lkml.kernel.org/r/1456061274-20059-2-git-send-email-sergey.senozhatsky@gmail.com > > in short, 3261 is good, but not as good as it possibly can be. for the > time being, our huge-class watermark starts at 3264. but this can > change. > > > a side note, I think we have sort of wrong API. zsmalloc knows better which > object is huge. and who knows, may be we will change the number of huge > classes someday or huge-class watermark, etc. so having "hey zsmalloc, is > this object huge or not" API seems to be better than ZRAM's enforcement > "hey zsmalloc, this object is huge". and yes, I think I'd like to reduce the number of huge classes right now we store objects [3264+, 4096] in huge clases. with this patch lkml.kernel.org/r/1456061274-20059-4-git-send-email-sergey.senozhatsky@gmail.com we have extra classes and smaller huge-class-range. so we store objects [3840+, 4096] in huge classes. less huge classes - more compressed objects; more compressed objects - lower memory usage. -ss