linux-kernel - [PATCH 2/3] lguest: more lazy

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Date:	Thu, 31 May 2007 17:24:13 +1000
From:	Rusty Russell <rusty@...tcorp.com.au>
To:	lkml - Kernel Mailing List <linux-kernel@...r.kernel.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	virtualization <virtualization@...ts.linux-foundation.org>
Subject: [PATCH 2/3] lguest: more lazy_hcalls

Some hypercalls can be batched: lazy_hcall is the wrapper which
determines this, so it's pretty harmless to use lazy_hcall() instead of
hcall().

Before:
Time for one context switch via pipe: 6745 (6521 - 13966)

After:
Time for one context switch via pipe: 5406 (5170 - 7467)

Signed-off-by: Rusty Russell <rusty@...tcorp.com.au>
---
 drivers/lguest/lguest.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

===================================================================
--- a/drivers/lguest/lguest.c
+++ b/drivers/lguest/lguest.c
@@ -225,7 +225,7 @@ static unsigned long current_cr0, curren
 static unsigned long current_cr0, current_cr3;
 static void lguest_write_cr0(unsigned long val)
 {
-	hcall(LHCALL_TS, val & 8, 0, 0);
+	lazy_hcall(LHCALL_TS, val & 8, 0, 0);
 	current_cr0 = val;
 }
 
@@ -247,7 +247,7 @@ static unsigned long lguest_read_cr2(voi
 
 static void lguest_write_cr3(unsigned long cr3)
 {
-	hcall(LHCALL_NEW_PGTABLE, cr3, 0, 0);
+	lazy_hcall(LHCALL_NEW_PGTABLE, cr3, 0, 0);
 	current_cr3 = cr3;
 }
 
@@ -287,7 +287,7 @@ static void lguest_set_pte(pte_t *ptep, 
 	*ptep = pteval;
 	/* Don't bother with hypercall before initial setup. */
 	if (current_cr3)
-		hcall(LHCALL_FLUSH_TLB, 1, 0, 0);
+		lazy_hcall(LHCALL_FLUSH_TLB, 1, 0, 0);
 }
 
 static void lguest_flush_tlb_single(unsigned long addr)


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