From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 3678A2C007D for ; Tue, 25 Sep 2012 23:32:55 +1000 (EST) In-Reply-To: <1348530909.25867.29@snotra> References: <1348530909.25867.29@snotra> Mime-Version: 1.0 (Apple Message framework v753.1) Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed Message-Id: <370AE837-07FF-4A85-9524-66D8EE185C40@kernel.crashing.org> From: Segher Boessenkool Subject: Re: Probing for native availability of isel from userspace Date: Tue, 25 Sep 2012 15:31:40 +0200 To: Scott Wood Cc: malc , linuxppc-dev@lists.ozlabs.org, hollis@penguinppc.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , >> That's for 64-bit; another good option for 64-bit is to just never >> use >> isel, it hardly ever buys you anything. It is much more useful on >> the >> (older) 32-bit cores that support it. > > Why is it more useful on 32-bit? If you're referring to the > performance of specific cores rather than some architectural thing, > maybe that's true with some chips, but on the Freescale side I'd be > surprised if e5500 were much different from e500v2 in that regard. Yes, I was talking about the older cores. I'd be surprised if ISEL is often a win on e5500, but I don't really know. I forgot about that chip to tell you the truth :-) Segher