From mboxrd@z Thu Jan 1 00:00:00 1970 From: Linus Torvalds Subject: Re: [Bug #14388] keyboard under X with 2.6.31 Date: Tue, 13 Oct 2009 08:41:23 -0700 (PDT) Message-ID: References: <56acieJJ2fF.A.nEB.Hzl0KB@chimera> <87ljjgfcbu.fsf@spindle.srvr.nix> <20091013113232.384b2432@lxorguk.ukuu.org.uk> <1255447980.3898.3.camel@x2.microgate.com> Mime-Version: 1.0 Return-path: In-Reply-To: <1255447980.3898.3.camel@x2.microgate.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: Content-Type: TEXT/PLAIN; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Paul Fulghum Cc: Alan Cox , Nix , "Justin P. Mattock" , "Rafael J. Wysocki" , Linux Kernel Mailing List , Kernel Testers List , Boyan , Dmitry Torokhov , Ed Tomlinson , =?ISO-8859-15?Q?Fr=E9d=E9ric_L=2E_W=2E_Meunier?= , OGAWA Hirofumi On Tue, 13 Oct 2009, Paul Fulghum wrote: > On Tue, 2009-10-13 at 07:39 -0700, Linus Torvalds wrote: > > It's not a f*cking performance tweak, and you're ludicrous to claim it is. > > It's pointless, and it's making the code _slower_ rather than faster. > > > > Lookie here, Alan - the common sequence is crap like this: > > > > tty_buffer_request_room(tty, buf->size); > > tty_insert_flip_string(tty, buf->base, buf->size); > > The performance tweak of tty_prepare_xxx is that you fill > the tty_buffer directly instead of writing data first to a staging > buffer and then calling tty_insert_flip_string, which just copies > from the staging buffer to the tty_buffer. So it saves a copy operation. Read the above again. Read what that common sequence is. Please just READ the f*cking code, and read my emails, instead of talking about something totally different that I'm not talking about at all. The _most_common_ use of "tty_buffer_request_room()" is literally just the above insane sequence I quoted, not the case you talk about at all. Don't believe me? Use grep. What _you_ are talking about is something else, namely the tty_prepare_flip stuff. But dammit, that has nothing what-so-ever to do with "tty_buffer_request_room()". What I was pointing out is that there are a lot of "tty_buffer_request_room()" calls, and as far as I can see, all of them (or at least a large percentage) are just pure and utter crap. Linus