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From: Alex <akhripin@mit.edu>
To: linux-kernel@vger.kernel.org
Subject: Slight optimizations to entry.S patch
Date: Thu, 20 Dec 2001 17:32:21 -0500	[thread overview]
Message-ID: <20011220223221.GA17913@morgoth.mit.edu> (raw)

Hi,
I was familiarizing (or trying to) myself with the i386 architecture code,
and saw a few possible optimizations. I think they can save a few cycles (not
that many). Can someone comment? Are the changes worthwhile?
-Alex K.

--- entry.S.orig	Thu Dec 20 16:57:39 2001
+++ entry.S	Thu Dec 20 17:20:29 2001
@@ -91,9 +91,9 @@
 	pushl %edi; \
 	pushl %esi; \
 	pushl %edx; \
+	movl $(__KERNEL_DS),%edx; \
 	pushl %ecx; \
 	pushl %ebx; \
-	movl $(__KERNEL_DS),%edx; \
 	movl %edx,%ds; \
 	movl %edx,%es;
 
@@ -141,13 +141,13 @@
 	movl EFLAGS(%esp),%ecx	# and this is cs..
 	movl %eax,EFLAGS(%esp)	#
 	movl %edx,EIP(%esp)	# Now we move them to their "normal" places
-	movl %ecx,CS(%esp)	#
 	movl %esp,%ebx
+	movl %ecx,CS(%esp)	#
 	pushl %ebx
 	andl $-8192,%ebx	# GET_CURRENT
 	movl exec_domain(%ebx),%edx	# Get the execution domain
-	movl 4(%edx),%edx	# Get the lcall7 handler for the domain
 	pushl $0x7
+	movl 4(%edx),%edx	# Get the lcall7 handler for the domain
 	call *%edx
 	addl $4, %esp
 	popl %eax
@@ -162,13 +162,13 @@
 	movl EFLAGS(%esp),%ecx	# and this is cs..
 	movl %eax,EFLAGS(%esp)	#
 	movl %edx,EIP(%esp)	# Now we move them to their "normal" places
-	movl %ecx,CS(%esp)	#
 	movl %esp,%ebx
+	movl %ecx,CS(%esp)	#
 	pushl %ebx
 	andl $-8192,%ebx	# GET_CURRENT
 	movl exec_domain(%ebx),%edx	# Get the execution domain
-	movl 4(%edx),%edx	# Get the lcall7 handler for the domain
 	pushl $0x27
+	movl 4(%edx),%edx	# Get the lcall7 handler for the domain
 	call *%edx
 	addl $4, %esp
 	popl %eax

             reply	other threads:[~2001-12-20 22:32 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2001-12-20 22:32 Alex [this message]
2001-12-20 22:47 ` Slight optimizations to entry.S patch Davide Libenzi
2001-12-20 23:55   ` Robert Love
2001-12-21 16:49 ` Alan Cox

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