Re: [Gems-users] flushing L1 caches


Date: Tue, 26 Feb 2008 16:29:21 +0100
From: Mladen Nikitovic <mladen@xxxxxx>
Subject: Re: [Gems-users] flushing L1 caches
Will do that. Thanks. Just wondered if there was anything semantically wrong with the code. I'm thinking about the way I've created the message and the way I've extracted the address from the cache. Does that seem as a reasonable approach?

I implemented the functions to extract the number of sets and ways and the address myself, there could be an error there. This is what I added to CacheMemory.h

template<class ENTRY>
inline
int CacheMemory<ENTRY>::getCacheNumSets()
{
 return m_cache_num_sets;
}

template<class ENTRY>
inline
int CacheMemory<ENTRY>::getCacheAssoc()
{
 return m_cache_assoc;
}

template<class ENTRY>
inline
Address CacheMemory<ENTRY>::getAddress(int i, int j)
{
 return m_cache[i][j].m_Address;
}

/M

Dan Gibson wrote:
This is a vector/array bounds assertion. Apparently some code in flush is accessing a Vector<L1Cache_Entry> with an offset too large for the specified size of the vector. As a first step, track down places were vectors are indexed in your call stack -- or better yet, attach gdb when you get the assertion and pop the call stack a few times to find the right spot.

Regards,
Dan

Mladen Nikitovic wrote:
> I have reproduced the error and this is the message I get from > Simics/GEMS when I try to do the flush:
>
>
> simics> c
> before flush (8023)
> failed assertion 'index < m_size' at fn TYPE& Vector<TYPE>::ref(int) > [with TYPE = L1Cache_Entry] in ../common/Vector.h:168 > failed assertion 'index < m_size' at fn TYPE& Vector<TYPE>::ref(int) > [with TYPE = L1Cache_Entry] in ../common/Vector.h:168
> At this point you might want to attach a debug to the running and get to the
> crash site; otherwise press enter to continue
> PID: 3981
> Warning: Interrupt key pressed more than once.
>          Pressing it again will force Simics back to the command prompt.
>          This may corrupt the running simulation.
>          Try waiting for Simics to stop first.
> USER INTERRUPT: Interrupt key pressed multiple times.
> Returning to prompt.
> simics>
>
>
> Hopefully this can help someone to shed some light on this matter.
>
> Best Regards,
> Mladen
>
> Mladen Nikitovic wrote:
> >> Hi,
>>
>> I'm trying to implement a function that flushes the L1 caches. You can >> see from my previous posts that I have arrived at a solution that >> involves some augmentation of protocol code etc. But, the final thing is >> actually implementing the flush in the Sequencer, which was supposed to >> be done be walking the I and D-cache entries and sending invalidation >> request via the mandatory queue. I have tried to do that but the >> simulation crashes when I try call the flush at the point of shutting >> down one of the processors.
>>
>> Implementation-wise, is there anything in the following function that >> should change?
>>
>> Thanks.
>>
>> Regards,
>> Mladen
>>
>> void Sequencer::flushL1caches(int cpu)
>> {
>>   Time latency = SEQUENCER_TO_CONTROLLER_LATENCY;
>>   CacheMsg Imsg, Dmsg;
>>   int i,j, Iassoc, Dassoc, Isets, Dsets;
>>
>>   Imsg.setType(CacheRequestType_INVALIDATE);
>>   Dmsg.setType(CacheRequestType_INVALIDATE);
>>
>> Isets = >> m_chip_ptr->m_L1Cache_L1IcacheMemory_vec[m_version]->getCacheNumSets(); >> Dsets = >> m_chip_ptr->m_L1Cache_L1DcacheMemory_vec[m_version]->getCacheNumSets();
>>
>> Iassoc = >> m_chip_ptr->m_L1Cache_L1IcacheMemory_vec[m_version]->getCacheAssoc(); >> Dassoc = >> m_chip_ptr->m_L1Cache_L1DcacheMemory_vec[m_version]->getCacheAssoc();
>>
>>   for(i=0; i<Isets; i++) {
>>     for(j=0; i<Iassoc; j++) {
>> >> Imsg.setAddress(m_chip_ptr->m_L1Cache_L1IcacheMemory_vec[m_version]->getAddress(i,j)); >> >> m_chip_ptr->m_L1Cache_mandatoryQueue_vec[m_version]->enqueue(Imsg, >> latency);
>>     }
>>   }
>>
>>   for(i=0; i<Dsets; i++) {
>>     for(j=0; i<Dassoc; j++) {
>> >> Dmsg.setAddress(m_chip_ptr->m_L1Cache_L1DcacheMemory_vec[m_version]->getAddress(i,j)); >> >> m_chip_ptr->m_L1Cache_mandatoryQueue_vec[m_version]->enqueue(Dmsg, >> latency);
>>     }
>>   }
>> }
>>
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>>
>> >> >
>
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>
--
http://www.cs.wisc.edu/~gibson [esc]:wq!

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