Date: | Tue, 18 Nov 2008 18:59:17 +0100 |
---|---|
From: | "Daniel Sánchez Pedreño" <sanatox@xxxxxxxxx> |
Subject: | [Gems-users] Low IPC in Opal |
Dear list, I have experimented a very low IPC when using Opal in GEMS 2.1. Around 0,6 when the processor width is 4. For example, for the FFT application from SPLASH-2 using just 1 processor, the results are: Total number of instructions 57450293 Total number of cycles 89828116 number of continue calls 57450293 Instruction per cycle: 0.639558 I have also seen that the fetch stage is usually stalled because of window full event, which represents around the 50% of the number of cycles of the simulation: Reasons for fetch stalls: Fetch ready : 0 0.00% Fetch i-cache miss : 1,553,619 2.73% Fetch squash : 167 0.00% Fetch I-TLB miss : 20,351 0.04% Window Full : 43,860,074 77.14% Fetch Barrier : 11,421,297 20.09% Write Buffer Full : 0 0.00% However, the ROB size in this experiment is 1024 entries while the window size is 512. Additionally,The L1 cache miss ratio is 3%. Finally, the Retire stage is stalled because of the following events: Retire Not-Ready Stage Histogram FETCH_STAGE = 201993 ( 0.249%) DECODE_STAGE = 202944 ( 0.250%) READY_STAGE = 8931472 (11.022%) EXECUTE_STAGE = 35066395 (43.273%) CACHE_MISS_STAGE = 23505376 (29.006%) CACHE_NOTREADY_STAGE = 4287931 ( 5.291%) COMPLETE_STAGE = 8839216 (10.908%) So the question is: is correct this low IPC? From the results obtained, what can I do to increase performance?. Thank you. |
[← Prev in Thread] | Current Thread | [Next in Thread→] |
---|---|---|
|
Previous by Date: | [Gems-users] problems with checkpoint creation, Krishnaiah Gummidipudi |
---|---|
Next by Date: | Re: [Gems-users] Low IPC in Opal, Dan Gibson |
Previous by Thread: | Re: [Gems-users] link_latency Directory, Jesús Camacho Villanueva |
Next by Thread: | Re: [Gems-users] Low IPC in Opal, Dan Gibson |
Indexes: | [Date] [Thread] |