x86: fix incorrect __read_mostly on _boot_cpu_pda
authorRavikiran G Thirumalai <kiran@scalex86.org>
Wed, 31 Dec 2008 21:44:46 +0000 (13:44 -0800)
committerIngo Molnar <mingo@elte.hu>
Fri, 2 Jan 2009 16:16:29 +0000 (17:16 +0100)
The pda rework (commit 3461b0af025251bbc6b3d56c821c6ac2de6f7209)
to remove static boot cpu pdas introduced a performance bug.

_boot_cpu_pda is the actual pda used by the boot cpu and is definitely
not "__read_mostly" and ended up polluting the read mostly section with
writes.  This bug caused regression of about 8-10% on certain syscall
intensive workloads.

Signed-off-by: Ravikiran Thirumalai <kiran@scalex86.org>
Acked-by: Mike Travis <travis@sgi.com>
Cc: <stable@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
arch/x86/kernel/head64.c

index 388e05a5fc17ec05dc68fc881c169608390538b5..b9a4d8c4b93529b3c568c054755d04d1f2534581 100644 (file)
@@ -27,7 +27,7 @@
 #include <asm/trampoline.h>
 
 /* boot cpu pda */
-static struct x8664_pda _boot_cpu_pda __read_mostly;
+static struct x8664_pda _boot_cpu_pda;
 
 #ifdef CONFIG_SMP
 /*