我是一個多年的linux kernel programmer, 長時間在撰寫high performance IO的系統程式,
最近我購買了底下新一代系統, 但意外的發現, /dev/ram0 的存取速度變得異常的慢
(相較於上一代的cpu e.g. Intel(R) Core(TM) i7-4790K CPU @ 4.00GHz + ddr3)
主機板是ASROCK的X99系列. (無超頻3.5GHz or 超頻4.0GHz都一樣)
DRAM是 F4-2400C15Q-32GRR (無超頻2133 或是 設定為XMP2.0 2400Hz 結果都一樣)
CPU是 Intel(R) Core(TM) i7-5930K CPU @ 3.50GHz
OS: Centos 7.0 / Centos 6.5 / Fedora 14 / Fedora 20 (都一樣的結果)
可以懷疑的對象包含OS, cpu, ram...
我換過多的linux kernel / distribution 並沒有差異
於是剩下cpu/ram , 我使用linux下知名的benchmark程式 sysbench
測cpu時與i7-4790k也沒有太大的差異
但使用sysbench作memory 速度測試 (底下有附測試結果)
得到的結果竟然只有 391568.72 ops/sec
i7-4790k + ddr3 ram (沒有超頻) 就有2462328.18 ops/sec
慢了將近8倍 !!!
請問一下這個問題有人知道遇過或知道原因嗎?? 謝謝.
ps. 如果把--memory-block-size=4K 放大到4096K
則速度就只略輸一點2882 ops/sec < 3265 ops/sec (差這一點是還OK)
yum install sysbench (安裝sysbench)
sysbench --test=memory --memory-block-size=4K --memory-total-size=10G run
sysbench 0.4.10: multi-threaded system evaluation benchmark
Running the test with following options:
Number of threads: 1
Doing memory operations speed test
Memory block size: 4K
Memory transfer size: 10240M
Memory operations type: write
Memory scope type: global
Threads started!
Done.
Operations performed: 2621440 (391568.72 ops/sec)
10240.00 MB transferred (1529.57 MB/sec)
Test execution summary:
total time: 6.6947s
total number of events: 2621440
total time taken by event execution: 5.2050
per-request statistics:
min: 0.00ms
avg: 0.00ms
max: 0.29ms
approx. 95 percentile: 0.00ms
Threads fairness:
events (avg/stddev): 2621440.0000/0.00
execution time (avg/stddev): 5.2050/0.00
最近我購買了底下新一代系統, 但意外的發現, /dev/ram0 的存取速度變得異常的慢
(相較於上一代的cpu e.g. Intel(R) Core(TM) i7-4790K CPU @ 4.00GHz + ddr3)
主機板是ASROCK的X99系列. (無超頻3.5GHz or 超頻4.0GHz都一樣)
DRAM是 F4-2400C15Q-32GRR (無超頻2133 或是 設定為XMP2.0 2400Hz 結果都一樣)
CPU是 Intel(R) Core(TM) i7-5930K CPU @ 3.50GHz
OS: Centos 7.0 / Centos 6.5 / Fedora 14 / Fedora 20 (都一樣的結果)
可以懷疑的對象包含OS, cpu, ram...
我換過多的linux kernel / distribution 並沒有差異
於是剩下cpu/ram , 我使用linux下知名的benchmark程式 sysbench
測cpu時與i7-4790k也沒有太大的差異
但使用sysbench作memory 速度測試 (底下有附測試結果)
得到的結果竟然只有 391568.72 ops/sec
i7-4790k + ddr3 ram (沒有超頻) 就有2462328.18 ops/sec
慢了將近8倍 !!!
請問一下這個問題有人知道遇過或知道原因嗎?? 謝謝.
ps. 如果把--memory-block-size=4K 放大到4096K
則速度就只略輸一點2882 ops/sec < 3265 ops/sec (差這一點是還OK)
yum install sysbench (安裝sysbench)
sysbench --test=memory --memory-block-size=4K --memory-total-size=10G run
sysbench 0.4.10: multi-threaded system evaluation benchmark
Running the test with following options:
Number of threads: 1
Doing memory operations speed test
Memory block size: 4K
Memory transfer size: 10240M
Memory operations type: write
Memory scope type: global
Threads started!
Done.
Operations performed: 2621440 (391568.72 ops/sec)
10240.00 MB transferred (1529.57 MB/sec)
Test execution summary:
total time: 6.6947s
total number of events: 2621440
total time taken by event execution: 5.2050
per-request statistics:
min: 0.00ms
avg: 0.00ms
max: 0.29ms
approx. 95 percentile: 0.00ms
Threads fairness:
events (avg/stddev): 2621440.0000/0.00
execution time (avg/stddev): 5.2050/0.00