From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e06smtp13.uk.ibm.com (e06smtp13.uk.ibm.com [195.75.94.109]) (using TLSv1 with cipher CAMELLIA256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 7D6261A115C for ; Wed, 27 May 2015 19:01:47 +1000 (AEST) Received: from /spool/local by e06smtp13.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 27 May 2015 10:01:42 +0100 Received: from b06cxnps4076.portsmouth.uk.ibm.com (d06relay13.portsmouth.uk.ibm.com [9.149.109.198]) by d06dlp02.portsmouth.uk.ibm.com (Postfix) with ESMTP id C4EA7219005C for ; Wed, 27 May 2015 10:01:18 +0100 (BST) Received: from d06av10.portsmouth.uk.ibm.com (d06av10.portsmouth.uk.ibm.com [9.149.37.251]) by b06cxnps4076.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id t4R91bin25296898 for ; Wed, 27 May 2015 09:01:38 GMT Received: from d06av10.portsmouth.uk.ibm.com (localhost [127.0.0.1]) by d06av10.portsmouth.uk.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id t4R91bil014028 for ; Wed, 27 May 2015 03:01:37 -0600 Date: Wed, 27 May 2015 11:01:32 +0200 From: Greg Kurz To: Nikunj A Dadhania Cc: linuxppc-dev@lists.ozlabs.org, Alexey Kardashevskiy , David Gibson Subject: Re: [PATCH] fbuffer: improve toggle cursor performance Message-ID: <20150527110132.430fff05@bahia.local> In-Reply-To: <87egm2a9lh.fsf@abhimanyu.in.ibm.com> References: <20150527001113.2506.23159.stgit@bahia.huguette.org> <87egm2a9lh.fsf@abhimanyu.in.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Wed, 27 May 2015 10:41:06 +0530 Nikunj A Dadhania wrote: > Greg Kurz writes: > > > SLOF currently calls hv-logical-load and hv-logical-store for every pixel > > when enabling or disabling the cursor. This is suboptimal when writing one > > char at a time to the console since terminal-write always toggles the cursor. > > And this is precisely what grub is doing when the user wants to edit a menu > > entry... the result is an incredibly slow and barely usable interface. > > > > The inner loop in fb8-toggle-cursor handles a contiguous region: it can be > > converted to hv-logical-memop. The result is 32 times less hcalls per char > > and a serious improvement in grub usability. > > > > Signed-off-by: Greg Kurz > > --- > > slof/fs/fbuffer.fs | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/slof/fs/fbuffer.fs b/slof/fs/fbuffer.fs > > index 756f05a..46b59bf 100644 > > --- a/slof/fs/fbuffer.fs > > +++ b/slof/fs/fbuffer.fs > > @@ -99,8 +99,8 @@ CREATE bitmap-buffer 400 4 * allot > > : fb8-toggle-cursor ( -- ) > > line# fb8-line2addr column# fb8-columns2bytes + > > char-height 0 ?DO > > - char-width screen-depth * 0 ?DO dup dup rb@ -1 xor swap rb! 1+ LOOP > > - screen-width screen-depth * + char-width screen-depth * - > > + dup dup 0 char-width screen-depth * 1 hv-logical-memop drop > > + screen-width screen-depth * + > > Why did you drop "char-width screen-depth * -" in the new code? This is > not me mentioned in the description. > This is because the current inner loop increments the address. When the loop ends, we're pointing at the next char, that is char-width * screen-depth bytes too far. In the new code, the address is duped on the stack before calling hv-logical-memop, so we don't need to fix it when proceeding to next line. In my first attempt, I forgot to drop the subtraction and got an interesting visual result :) > Regards > Nikunj Cheers. -- Greg