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[PATCH] msr.c: use smp_call_function_single() [message #9694] Wed, 17 January 2007 12:52 Go to next message
adobriyan is currently offline  adobriyan
Messages: 80
Registered: November 2006
Member
It will execute rdmsr and wrmsr only on the cpu we need.

Signed-off-by: Alexey Dobriyan <adobriyan@openvz.org>
---

arch/i386/kernel/msr.c | 13 ++++---------
1 file changed, 4 insertions(+), 9 deletions(-)

--- a/arch/i386/kernel/msr.c
+++ b/arch/i386/kernel/msr.c
@@ -68,7 +68,6 @@ static inline int rdmsr_eio(u32 reg, u32
#ifdef CONFIG_SMP

struct msr_command {
- int cpu;
int err;
u32 reg;
u32 data[2];
@@ -78,16 +77,14 @@ static void msr_smp_wrmsr(void *cmd_bloc
{
struct msr_command *cmd = (struct msr_command *)cmd_block;

- if (cmd->cpu == smp_processor_id())
- cmd->err = wrmsr_eio(cmd->reg, cmd->data[0], cmd->data[1]);
+ cmd->err = wrmsr_eio(cmd->reg, cmd->data[0], cmd->data[1]);
}

static void msr_smp_rdmsr(void *cmd_block)
{
struct msr_command *cmd = (struct msr_command *)cmd_block;

- if (cmd->cpu == smp_processor_id())
- cmd->err = rdmsr_eio(cmd->reg, &cmd->data[0], &cmd->data[1]);
+ cmd->err = rdmsr_eio(cmd->reg, &cmd->data[0], &cmd->data[1]);
}

static inline int do_wrmsr(int cpu, u32 reg, u32 eax, u32 edx)
@@ -99,12 +96,11 @@ static inline int do_wrmsr(int cpu, u32
if (cpu == smp_processor_id()) {
ret = wrmsr_eio(reg, eax, edx);
} else {
- cmd.cpu = cpu;
cmd.reg = reg;
cmd.data[0] = eax;
cmd.data[1] = edx;

- smp_call_function(msr_smp_wrmsr, &cmd, 1, 1);
+ smp_call_function_single(cpu, msr_smp_wrmsr, &cmd, 1, 1);
ret = cmd.err;
}
preempt_enable();
@@ -120,10 +116,9 @@ static inline int do_rdmsr(int cpu, u32
if (cpu == smp_processor_id()) {
ret = rdmsr_eio(reg, eax, edx);
} else {
- cmd.cpu = cpu;
cmd.reg = reg;

- smp_call_function(msr_smp_rdmsr, &cmd, 1, 1);
+ smp_call_function_single(cpu, msr_smp_rdmsr, &cmd, 1, 1);

*eax = cmd.data[0];
*edx = cmd.data[1];
Re: [PATCH] msr.c: use smp_call_function_single() [message #9729 is a reply to message #9694] Thu, 18 January 2007 22:53 Go to previous message
hpa is currently offline  hpa
Messages: 38
Registered: January 2007
Member
Alexey Dobriyan wrote:
> It will execute rdmsr and wrmsr only on the cpu we need.
>
> Signed-off-by: Alexey Dobriyan <adobriyan@openvz.org>

This is good, but a bit incomplete; see other message recently posted to
LKML. Since this affects paravirtualization I want to minimize the
number of changes.

-hpa
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