From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755341AbcECG7f (ORCPT ); Tue, 3 May 2016 02:59:35 -0400 Received: from mail-pf0-f194.google.com ([209.85.192.194]:33712 "EHLO mail-pf0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751090AbcECG7e (ORCPT ); Tue, 3 May 2016 02:59:34 -0400 Date: Tue, 3 May 2016 16:01:08 +0900 From: Sergey Senozhatsky To: Minchan Kim Cc: Sergey Senozhatsky , Sergey Senozhatsky , Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] zram: user per-cpu compression streams Message-ID: <20160503070108.GE25545@swordfish> References: <1461860230-849-1-git-send-email-sergey.senozhatsky@gmail.com> <1461860230-849-3-git-send-email-sergey.senozhatsky@gmail.com> <20160502062311.GB6077@bbox> <20160502072508.GA1811@swordfish> <20160502080600.GB1811@swordfish> <20160503052324.GB17316@bbox> <20160503054011.GA5972@blaptop> <20160503055715.GC25545@swordfish> <20160503061823.GA6062@blaptop> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160503061823.GA6062@blaptop> User-Agent: Mutt/1.6.0 (2016-04-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On (05/03/16 15:19), Minchan Kim wrote: > > > > cat /sys/xxx/max_comp_stream returns num_online_cpus. > > > > > > One more thing, > > > > > > User: > > > echo 4 > /sys/xxx/max_comp_stream" > > > cat /sys/xxx/max_comp_streams > > > 8 > > > > sure, it can also be > > > > cat /sys/xxx/max_comp_streams > > 5 > > cat /sys/xxx/max_comp_streams > > 6 > > cat /sys/xxx/max_comp_streams > > 7 > > cat /sys/xxx/max_comp_streams > > 3 > > > > depending on the availability of CPUs. but why would user space > > constantly check max_comp_streams? > > > > > which is rather weird? > > > > > > We should keep user's value and return it to user although it's techically > > > lying. IMO, it would be best way to prevent confusing for user until we > > > removes max_comp_streams finally. > > > > well, I preferred to show the actual state of the device. besides, > > does anyone really do > > > > write buffer to file > > if (success) > > read from file and compare with the buffer > > > > ? > > > > Okay, I want to go with your approach! thanks. I mean that was my thinking when I decided to change the max_comp_streams output. but no pressure, it does change the numbers that user space will see. don't have any strong opinion, can keep it as zcomp cleanup only -- w/o touching the _show()/_store() parts. > Could you update zram.txt to reflect it? will do later today. I think I'd prefer to keep it as independent patch, since it does change the user visible behaviour after all (no idea if it's true tho; can't easily think why would anyone keep track of the values returned by cat /sys/xxx/max_comp_streams), so we can revert it w/o reverting the per-cpu streams IF anyone/anything will get upset with the change. -ss