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 ESMTP id 9602D67B17 for ; Sun, 11 Jun 2006 08:25:05 +1000 (EST) Subject: Re: [PATCH] powerpc: system call micro optimisation From: Benjamin Herrenschmidt To: Anton Blanchard In-Reply-To: <20060610151555.GV23891@krispykreme> References: <20060610151555.GV23891@krispykreme> Content-Type: text/plain Date: Sun, 11 Jun 2006 08:24:58 +1000 Message-Id: <1149978298.12687.152.camel@localhost.localdomain> Mime-Version: 1.0 Cc: linuxppc-dev@ozlabs.org, paulus@samba.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Sun, 2006-06-11 at 01:15 +1000, Anton Blanchard wrote: > In the syscall path we currently have: > > crclr so > mfcr r9 > > If we shift the crclr up we can avoid a stall on some CPUs. Can you maybe have a quick look at the vDSO's ? They might have similar room for optimisations... Cheers, Ben. > Signed-off-by: Anton Blanchard > --- > > Index: kernel/arch/powerpc/kernel/entry_64.S > =================================================================== > --- kernel.orig/arch/powerpc/kernel/entry_64.S 2006-04-26 08:03:05.380651922 -0500 > +++ kernel/arch/powerpc/kernel/entry_64.S 2006-04-26 08:03:28.076523958 -0500 > @@ -59,6 +59,7 @@ system_call_common: > beq- 1f > ld r1,PACAKSAVE(r13) > 1: std r10,0(r1) > + crclr so > std r11,_NIP(r1) > std r12,_MSR(r1) > std r0,GPR0(r1) > @@ -77,7 +78,6 @@ system_call_common: > std r11,GPR11(r1) > std r11,GPR12(r1) > std r9,GPR13(r1) > - crclr so > mfcr r9 > mflr r10 > li r11,0xc01 > _______________________________________________ > Linuxppc-dev mailing list > Linuxppc-dev@ozlabs.org > https://ozlabs.org/mailman/listinfo/linuxppc-dev