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Re: [Qemu-devel] [PATCH 05/10] tcg: Prepare TB invalidation for lockless
From: |
Sergey Fedorov |
Subject: |
Re: [Qemu-devel] [PATCH 05/10] tcg: Prepare TB invalidation for lockless TB lookup |
Date: |
Thu, 21 Jul 2016 11:36:35 +0300 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.8.0 |
On 20/07/16 01:27, Paolo Bonzini wrote:
>
> ----- Original Message -----
>> From: "Sergey Fedorov" <address@hidden>
>> To: "Paolo Bonzini" <address@hidden>, address@hidden
>> Cc: "sergey fedorov" <address@hidden>, "alex bennee" <address@hidden>
>> Sent: Tuesday, July 19, 2016 9:56:49 PM
>> Subject: Re: [PATCH 05/10] tcg: Prepare TB invalidation for lockless TB
>> lookup
>>
>> On 19/07/16 11:32, Paolo Bonzini wrote:
>> It looks much better now :)
>>
>>> When invalidating a translation block, set an invalid flag into the
>>> TranslationBlock structure first. It is also necessary to check whether
>>> the target TB is still valid after acquiring 'tb_lock' but before calling
>>> tb_add_jump() since TB lookup is to be performed out of 'tb_lock' in
>>> future. Note that we don't have to check 'last_tb'; an already invalidated
>>> TB will not be executed anyway and it is thus safe to patch it.
>>>
>>> Suggested-by: Sergey Fedorov <address@hidden>
>>> Signed-off-by: Paolo Bonzini <address@hidden>
>>> ---
>>> cpu-exec.c | 5 +++--
>>> include/exec/exec-all.h | 2 ++
>>> translate-all.c | 3 +++
>>> 3 files changed, 8 insertions(+), 2 deletions(-)
>> (snip)
>>> diff --git a/include/exec/exec-all.h b/include/exec/exec-all.h
>>> index acda7b6..bc0bcc5 100644
>>> --- a/include/exec/exec-all.h
>>> +++ b/include/exec/exec-all.h
>>> @@ -213,6 +213,8 @@ struct TranslationBlock {
>>> #define CF_USE_ICOUNT 0x20000
>>> #define CF_IGNORE_ICOUNT 0x40000 /* Do not generate icount code */
>>>
>>> + uint16_t invalid;
>> Why not "int"?
> There's a hole there, we may want to move something else so I
> used a smaller data type. Even uint8_t would do.
But could simple "bool" work as well here?
>
> Paolo
>>> +
>>> void *tc_ptr; /* pointer to the translated code */
>>> uint8_t *tc_search; /* pointer to search data */
Are you sure that the hole is over there, not here?
Kind regards,
Sergey
>>> /* original tb when cflags has CF_NOCACHE */
>>>
>> Thanks,
>> Sergey
>>
[Qemu-devel] [PATCH 03/10] tcg: Prepare safe tb_jmp_cache lookup out of tb_lock, Paolo Bonzini, 2016/07/19
[Qemu-devel] [PATCH 04/10] tcg: Prepare safe access to tb_flushed out of tb_lock, Paolo Bonzini, 2016/07/19
[Qemu-devel] [PATCH 06/10] tcg: set up tb->page_addr before insertion, Paolo Bonzini, 2016/07/19
[Qemu-devel] [PATCH 08/10] tcg: Avoid bouncing tb_lock between tb_gen_code() and tb_add_jump(), Paolo Bonzini, 2016/07/19
[Qemu-devel] [PATCH 10/10] tcg: rename tb_find_physical(), Paolo Bonzini, 2016/07/19
[Qemu-devel] [PATCH 09/10] tcg: Merge tb_find_slow() and tb_find_fast(), Paolo Bonzini, 2016/07/19
[Qemu-devel] [PATCH 07/10] tcg: cpu-exec: remove tb_lock from the hot-path, Paolo Bonzini, 2016/07/19