From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Mon, 9 Jan 2017 10:09:20 -0500 (EST) From: Jerome Marchand To: Sergey Senozhatsky Cc: Minchan Kim , Jens Axboe , Hyeoncheol Lee , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, Andrew Morton , Robert Jennings Message-ID: <978119764.6177321.1483974560473.JavaMail.zimbra@redhat.com> In-Reply-To: <20170109143344.GA753@tigerII.localdomain> References: <1483938267-8858-1-git-send-email-minchan@kernel.org> <20170109143344.GA753@tigerII.localdomain> Subject: Re: [RFC] blk: increase logical_block_size to unsigned int MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 List-ID: ----- Original Message ----- > From: "Sergey Senozhatsky" > To: "Minchan Kim" > Cc: "Jens Axboe" , "Hyeoncheol Lee" , linux-block@vger.kernel.org, > linux-kernel@vger.kernel.org, "Andrew Morton" , "Sergey Senozhatsky" > , "Robert Jennings" , "Jerome Marchand" > Sent: Monday, January 9, 2017 3:33:44 PM > Subject: Re: [RFC] blk: increase logical_block_size to unsigned int > > On (01/09/17 14:04), Minchan Kim wrote: > > Mostly, zram is used as swap system on embedded world so it want to do IO > > as PAGE_SIZE aligned/size IO unit. For that, one of the problem was > > blk_queue_logical_block_size(zram->disk->queue, PAGE_SIZE) made overflow > > in *64K page system* so [1] changed it to constant 4096. > > Since that, partial IO can happen so zram should handle it which makes zram > > complicated[2]. > > > > I thought that zram partial IO support is there because some file > systems cannot cope with large logical_block_size. like FAT, for > example. am I wrong? Yes indeed. When we discussed the patch adding the partial I/O, increasing the size of logical_block was considered. The reason we didn't go the easy path was that not all block users could handle 64k blocks. FAT is one of them. Jerome > > -ss >