Re: [Qemu-devel] [RFC PATCH V6 18/18] translate-all: (wip) use tb_flush_safe when we can't alloc more tb.

[Frederic Konrad <fred.konrad@greensocs.com>]

On 07/07/2015 18:17, Alex Bennée wrote:
> fred.konrad@greensocs.com writes:
>
>> From: KONRAD Frederic <fred.konrad@greensocs.com>
>>
>> This changes just the tb_flush called from tb_alloc.
>>
>> TODO:
>>   * changes the other tb_flush.
>>
>> Signed-off-by: KONRAD Frederic <fred.konrad@greensocs.com>
>> ---
>>   translate-all.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/translate-all.c b/translate-all.c
>> index 8bd8fe8..9adaffa 100644
>> --- a/translate-all.c
>> +++ b/translate-all.c
>> @@ -1147,7 +1147,7 @@ TranslationBlock *tb_gen_code(CPUState *cpu,
>>       tb = tb_alloc(pc);
>>       if (!tb) {
>>           /* flush must be done */
>> -        tb_flush(env);
>> +        tb_flush_safe(env);
> Hold on this is async right? What stops us rolling on and then getting
> flushed when the other vCPUs come to a halt?
>
> It deserves a comment at least.
>

not this need some synchronization when the CPUs are halted.
There is crap here spotted by Paolo though.

In the case of tb_flush.. We do an async_safe_work because all VCPUs thread
must be outside cpu_exec.

Are you suggesting to just exiting everybody and wait here that all 
VCPUs exit?
This is possible as well here but is not possible for the other case.. 
That's why I
prefered a "generic" mechanism.

Fred
>>           /* cannot fail at this point */
>>           tb = tb_alloc(pc);
>>           /* Don't forget to invalidate previous TB info.  */