From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Mon, 21 Sep 2020 18:12:24 +0200 From: Christoph Hellwig Subject: Re: [PATCH 02/11] mm: call import_iovec() instead of rw_copy_check_uvector() in process_vm_rw() Message-ID: <20200921161224.GA24807@lst.de> References: <20200921143434.707844-1-hch@lst.de> <20200921143434.707844-3-hch@lst.de> <20200921150211.GS3421308@ZenIV.linux.org.uk> <20200921152937.GX3421308@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200921152937.GX3421308@ZenIV.linux.org.uk> List-ID: To: Al Viro Cc: David Laight , Christoph Hellwig , Andrew Morton , Jens Axboe , Arnd Bergmann , David Howells , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "linux-mips@vger.kernel.org" , "linux-parisc@vger.kernel.org" , "linuxppc-dev@lists.ozlabs.org" , "linux-s390@vger.kernel.org" , "sparclinux@vger.kernel.org" , "linux-block@vger.kernel.org" , "linux-scsi@vger.kernel.org" , "linux-fsdevel@vger.kernel.org" , "linux-aio@kvack.org" , "io-uring@vger.kernel.org" , "linux-arch@vger.kernel.org" , "linux-mm@kvack.org" , "netdev@vger.kernel.org" , "keyrings@vger.kernel.org" , "linux-security-module@vger.kernel.org" On Mon, Sep 21, 2020 at 04:29:37PM +0100, Al Viro wrote: > On Mon, Sep 21, 2020 at 03:21:35PM +0000, David Laight wrote: > > > You really don't want to be looping through the array twice. > > Profiles, please. Given that the iov array should be cache hot I'd be surprised to see a huge difference.