diff options
| -rw-r--r-- | src/mem/cache/cache_impl.hh | 48 |
1 files changed, 22 insertions, 26 deletions
diff --git a/src/mem/cache/cache_impl.hh b/src/mem/cache/cache_impl.hh index ec438bc50..745fe38bf 100644 --- a/src/mem/cache/cache_impl.hh +++ b/src/mem/cache/cache_impl.hh @@ -1887,39 +1887,33 @@ template<class TagStore> MSHR * Cache<TagStore>::getNextMSHR() { - // Check both MSHR queue and write buffer for potential requests + // Check both MSHR queue and write buffer for potential requests, + // note that null does not mean there is no request, it could + // simply be that it is not ready MSHR *miss_mshr = mshrQueue.getNextMSHR(); MSHR *write_mshr = writeBuffer.getNextMSHR(); - // Now figure out which one to send... some cases are easy - if (miss_mshr && !write_mshr) { - return miss_mshr; - } - if (write_mshr && !miss_mshr) { - return write_mshr; - } - - if (miss_mshr && write_mshr) { - // We have one of each... normally we favor the miss request - // unless the write buffer is full - if (writeBuffer.isFull() && writeBuffer.inServiceEntries == 0) { - // Write buffer is full, so we'd like to issue a write; - // need to search MSHR queue for conflicting earlier miss. - MSHR *conflict_mshr = - mshrQueue.findPending(write_mshr->addr, write_mshr->size, - write_mshr->isSecure); + // If we got a write buffer request ready, first priority is a + // full write buffer, otherwhise we favour the miss requests + if (write_mshr && + ((writeBuffer.isFull() && writeBuffer.inServiceEntries == 0) || + !miss_mshr)) { + // need to search MSHR queue for conflicting earlier miss. + MSHR *conflict_mshr = + mshrQueue.findPending(write_mshr->addr, write_mshr->size, + write_mshr->isSecure); - if (conflict_mshr && conflict_mshr->order < write_mshr->order) { - // Service misses in order until conflict is cleared. - return conflict_mshr; - } + if (conflict_mshr && conflict_mshr->order < write_mshr->order) { + // Service misses in order until conflict is cleared. + return conflict_mshr; - // No conflicts; issue write - return write_mshr; + // @todo Note that we ignore the ready time of the conflict here } - // Write buffer isn't full, but need to check it for - // conflicting earlier writeback + // No conflicts; issue write + return write_mshr; + } else if (miss_mshr) { + // need to check for conflicting earlier writeback MSHR *conflict_mshr = writeBuffer.findPending(miss_mshr->addr, miss_mshr->size, miss_mshr->isSecure); @@ -1937,6 +1931,8 @@ Cache<TagStore>::getNextMSHR() // have to flush writes in order? I don't think so... not // for Alpha anyway. Maybe for x86? return conflict_mshr; + + // @todo Note that we ignore the ready time of the conflict here } // No conflicts; issue read |