[PATCH v7 2/2] Mutex: Replace trylock by read only while spinning

[kemi]

On 2018年07月11日 11:17, kemi wrote:
> Hi, Carlos
>>> Do you need to do a whole system performance measurement?
>>
>> I thought the data posted here is good enough to demonstrate the effectiveness of this patch.
>> But if you insist, I will try to do something to figure it out.
>>
> 
> To measure a whole system performance:
> 
> We run *two* processes with locking at the same time. Each process has multiple threads, and
> each thread do the following:
> a) lock
> b) delay 1000ns in the critical section
> c) unlock
> d) delay 6000ns in the non-critical section
> in a loop for 5 seconds, and measure the total iterations for each process.
> 
> Each test run 4 times with stable testing result.
> 
> Test result:
> threads           base(CAS)                     head(test and CAS)          
> 28                 1681975			 1813090(+7.8%)
> 
> 56		   1801954			 1890549(+4.9%)
> 
> ========================cut==========================================
> I also run a *single* process and post the test result as below (each test run 4 times with 
> stable testing result):
> threads           base(CAS)                    head(test and CAS)
> 28		   2262848                       2274362 (+0.5%)
> 
> 56		   1949439                       1994526 (+2.3%)
> 
> This is what I got in my test, this change is not a big optimization, but should have some 
> limited performance improvement. Additionally, the workload I run here is not so Macro 
　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　^~~~~
                                                                                    s/Macro/Micro
							                            Ignore the previous email
> (Some Micro benchmarks make the size of critical section and non-critical section extremely
>  small), so I believe this change is helpful with some practical workload.
> 
>