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[Qemu-devel] Re: [PATCH] A bit optimization for tlb_set_page()
From: |
Jun Koi |
Subject: |
[Qemu-devel] Re: [PATCH] A bit optimization for tlb_set_page() |
Date: |
Wed, 28 Apr 2010 16:13:57 +0900 |
On Wed, Apr 28, 2010 at 3:53 PM, Jan Kiszka <address@hidden> wrote:
> Jun Koi wrote:
>> On Wed, Apr 28, 2010 at 8:48 AM, Jun Koi <address@hidden> wrote:
>>> On Wed, Apr 28, 2010 at 3:36 AM, Jan Kiszka <address@hidden> wrote:
>>>> Jun Koi wrote:
>>>>> It is not necessary to continue searching for watchpoint when we
>>>>> already found one and setup for handling watchpoint in a search loop
>>>>> in tlb_set_page().
>>>>> This patch breaks that search loop on then.
>>>> Acked-by: Jan Kiszka <address@hidden>
>>>>
>>>>> Signed-off-by: Jun Koi <address@hidden>
>>>>>
>>>>> diff --git a/exec.c b/exec.c
>>>>> index 14d1fd7..6329775 100644
>>>>> --- a/exec.c
>>>>> +++ b/exec.c
>>>>> @@ -2240,6 +2240,7 @@ void tlb_set_page(CPUState *env, target_ulong vaddr,
>>>>> /* TODO: The memory case can be optimized by not trapping
>>>>> reads of pages with a write breakpoint. */
>>>> PS: Don't you also want to address this todo while you are at it? :)
>>>>
>>
>> Do you have any comment on below patch?
>>
>> Thanks,
>> J
>>
>>
>> Dont handle write watchpoints on read-only memory access.
>> This patch also breaks the searching loop for watchpoint once the
>> setup facilities for handling watchpoint later is done.
>>
>> Signed-off-by: Jun Koi <address@hidden>
>>
>> diff --git a/exec.c b/exec.c
>> index 14d1fd7..3f2d9ed 100644
>> --- a/exec.c
>> +++ b/exec.c
>> @@ -2236,10 +2236,12 @@ void tlb_set_page(CPUState *env, target_ulong vaddr,
>> watchpoint trap routines. */
>> QTAILQ_FOREACH(wp, &env->watchpoints, entry) {
>> if (vaddr == (wp->vaddr & TARGET_PAGE_MASK)) {
>> - iotlb = io_mem_watch + paddr;
>> - /* TODO: The memory case can be optimized by not trapping
>> - reads of pages with a write breakpoint. */
>> - address |= TLB_MMIO;
>> + /* Avoid trapping reads of pages with a write breakpoint. */
>> + if (!((prot & PAGE_WRITE == 0) && (wp->flags &
>> BP_MEM_WRITE != 0))) {
>
> Patch is line-wrapped.
That is the fault of Gmail.
> Besides that
>
> if ((wp->flags & BP_MEM_READ) || (prot & PAGE_WRITE))
>
> is more readable IMHO.
Agreed. Please see my updated patch.
Thanks,
Jun
Dont handle write watchpoints on read-only memory access.
This patch also breaks the searching loop for watchpoint once the
setup for handling watchpoint later is done.
Signed-off-by: Jun Koi <address@hidden>
diff --git a/exec.c b/exec.c
index 14d1fd7..6fd859f 100644
--- a/exec.c
+++ b/exec.c
@@ -2236,10 +2236,12 @@ void tlb_set_page(CPUState *env, target_ulong vaddr,
watchpoint trap routines. */
QTAILQ_FOREACH(wp, &env->watchpoints, entry) {
if (vaddr == (wp->vaddr & TARGET_PAGE_MASK)) {
- iotlb = io_mem_watch + paddr;
- /* TODO: The memory case can be optimized by not trapping
- reads of pages with a write breakpoint. */
- address |= TLB_MMIO;
+ /* Avoid trapping reads of pages with a write breakpoint. */
+ if ((prot & PAGE_WRITE) || (wp->flags & BP_MEM_READ)) {
+ iotlb = io_mem_watch + paddr;
+ address |= TLB_MMIO;
+ break;
+ }
}
}