From: Bob Picco <Robert.Picco@hp.com>
To: linux-ia64@vger.kernel.org
Subject: [PATCH] small optimization in ia64_leave_kernel
Date: Wed, 12 Jan 2005 01:39:29 +0000 [thread overview]
Message-ID: <20050112025259.GI6314@localhost.localdomain> (raw)
Hi Tony:
When returning to the kernel and not switching rbs, avoid fetching
local_cpu_data. More could possibly be optimized here but limited registers
are available and the number of bundles might increase. I didn't pursue any
further than predicating two instructions which eliminates a memory fetch.
thanks,
bob
Signed-off-by: Bob Picco <robert.picco@hp.com>
diff -ruNp -X /home/picco/losl/dontdiff linux-2.6.10-orig/arch/ia64/kernel/entry.S linux-2.6.10/arch/ia64/kernel/entry.S
--- linux-2.6.10-orig/arch/ia64/kernel/entry.S 2005-01-04 19:06:14.000000000 -0500
+++ linux-2.6.10/arch/ia64/kernel/entry.S 2005-01-08 15:47:45.000000000 -0500
@@ -925,9 +925,9 @@ GLOBAL_ENTRY(ia64_leave_kernel)
shr.u r18=r19,16 // get byte size of existing "dirty" partition
;;
mov r16=ar.bsp // get existing backing store pointer
- addl r17=THIS_CPU(ia64_phys_stacked_size_p8),r0
+(pUStk) addl r17=THIS_CPU(ia64_phys_stacked_size_p8),r0
;;
- ld4 r17=[r17] // r17 = cpu_data->phys_stacked_size_p8
+(pUStk) ld4 r17=[r17] // r17 = cpu_data->phys_stacked_size_p8
(pKStk) br.cond.dpnt skip_rbs_switch
/*
reply other threads:[~2005-01-12 1:39 UTC|newest]
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