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[Qemu-devel] Re: [PATCH] A bit optimization for tlb_set_page()
From: |
Jan Kiszka |
Subject: |
[Qemu-devel] Re: [PATCH] A bit optimization for tlb_set_page() |
Date: |
Wed, 28 Apr 2010 08:53:54 +0200 |
User-agent: |
Mozilla/5.0 (X11; U; Linux i686 (x86_64); de; rv:1.8.1.12) Gecko/20080226 SUSE/2.0.0.12-1.1 Thunderbird/2.0.0.12 Mnenhy/0.7.5.666 |
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. Besides that
if ((wp->flags & BP_MEM_READ) || (prot & PAGE_WRITE))
is more readable IMHO.
> + iotlb = io_mem_watch + paddr;
> + address |= TLB_MMIO;
> + break;
> + }
> }
> }
Thanks,
Jan
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