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authorLinus Torvalds <torvalds@woody.linux-foundation.org>2007-11-05 14:39:00 -0500
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-11-05 14:39:00 -0500
commit221d46841b931d0e6b11e6251e482f2afe3974dd (patch)
treefeb33999f71a84003f4ac752300c81f47f9e272f /arch
parent4d20826ffb6fa80c71b85d2cb858ae400a59a4d5 (diff)
parent633872b980f55f40a5e7de374f26970e41e2137b (diff)
Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-lguest
* 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-lguest: lguest: tidy up documentation kernel/futex.c: make 3 functions static unexport access_process_vm lguest: make async_hcall() static
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/lguest/boot.c69
1 files changed, 34 insertions, 35 deletions
diff --git a/arch/x86/lguest/boot.c b/arch/x86/lguest/boot.c
index a55b0902f9d3..92c56117eae5 100644
--- a/arch/x86/lguest/boot.c
+++ b/arch/x86/lguest/boot.c
@@ -93,38 +93,7 @@ struct lguest_data lguest_data = {
93}; 93};
94static cycle_t clock_base; 94static cycle_t clock_base;
95 95
96/*G:035 Notice the lazy_hcall() above, rather than hcall(). This is our first 96/*G:037 async_hcall() is pretty simple: I'm quite proud of it really. We have a
97 * real optimization trick!
98 *
99 * When lazy_mode is set, it means we're allowed to defer all hypercalls and do
100 * them as a batch when lazy_mode is eventually turned off. Because hypercalls
101 * are reasonably expensive, batching them up makes sense. For example, a
102 * large munmap might update dozens of page table entries: that code calls
103 * paravirt_enter_lazy_mmu(), does the dozen updates, then calls
104 * lguest_leave_lazy_mode().
105 *
106 * So, when we're in lazy mode, we call async_hypercall() to store the call for
107 * future processing. When lazy mode is turned off we issue a hypercall to
108 * flush the stored calls.
109 */
110static void lguest_leave_lazy_mode(void)
111{
112 paravirt_leave_lazy(paravirt_get_lazy_mode());
113 hcall(LHCALL_FLUSH_ASYNC, 0, 0, 0);
114}
115
116static void lazy_hcall(unsigned long call,
117 unsigned long arg1,
118 unsigned long arg2,
119 unsigned long arg3)
120{
121 if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE)
122 hcall(call, arg1, arg2, arg3);
123 else
124 async_hcall(call, arg1, arg2, arg3);
125}
126
127/* async_hcall() is pretty simple: I'm quite proud of it really. We have a
128 * ring buffer of stored hypercalls which the Host will run though next time we 97 * ring buffer of stored hypercalls which the Host will run though next time we
129 * do a normal hypercall. Each entry in the ring has 4 slots for the hypercall 98 * do a normal hypercall. Each entry in the ring has 4 slots for the hypercall
130 * arguments, and a "hcall_status" word which is 0 if the call is ready to go, 99 * arguments, and a "hcall_status" word which is 0 if the call is ready to go,
@@ -134,8 +103,8 @@ static void lazy_hcall(unsigned long call,
134 * full and we just make the hypercall directly. This has the nice side 103 * full and we just make the hypercall directly. This has the nice side
135 * effect of causing the Host to run all the stored calls in the ring buffer 104 * effect of causing the Host to run all the stored calls in the ring buffer
136 * which empties it for next time! */ 105 * which empties it for next time! */
137void async_hcall(unsigned long call, 106static void async_hcall(unsigned long call, unsigned long arg1,
138 unsigned long arg1, unsigned long arg2, unsigned long arg3) 107 unsigned long arg2, unsigned long arg3)
139{ 108{
140 /* Note: This code assumes we're uniprocessor. */ 109 /* Note: This code assumes we're uniprocessor. */
141 static unsigned int next_call; 110 static unsigned int next_call;
@@ -161,7 +130,37 @@ void async_hcall(unsigned long call,
161 } 130 }
162 local_irq_restore(flags); 131 local_irq_restore(flags);
163} 132}
164/*:*/ 133
134/*G:035 Notice the lazy_hcall() above, rather than hcall(). This is our first
135 * real optimization trick!
136 *
137 * When lazy_mode is set, it means we're allowed to defer all hypercalls and do
138 * them as a batch when lazy_mode is eventually turned off. Because hypercalls
139 * are reasonably expensive, batching them up makes sense. For example, a
140 * large munmap might update dozens of page table entries: that code calls
141 * paravirt_enter_lazy_mmu(), does the dozen updates, then calls
142 * lguest_leave_lazy_mode().
143 *
144 * So, when we're in lazy mode, we call async_hcall() to store the call for
145 * future processing. */
146static void lazy_hcall(unsigned long call,
147 unsigned long arg1,
148 unsigned long arg2,
149 unsigned long arg3)
150{
151 if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE)
152 hcall(call, arg1, arg2, arg3);
153 else
154 async_hcall(call, arg1, arg2, arg3);
155}
156
157/* When lazy mode is turned off reset the per-cpu lazy mode variable and then
158 * issue a hypercall to flush any stored calls. */
159static void lguest_leave_lazy_mode(void)
160{
161 paravirt_leave_lazy(paravirt_get_lazy_mode());
162 hcall(LHCALL_FLUSH_ASYNC, 0, 0, 0);
163}
165 164
166/*G:033 165/*G:033
167 * After that diversion we return to our first native-instruction 166 * After that diversion we return to our first native-instruction