linux 磁盘io测试问题？

embed

[root@rac1 temp]# pwd
/home/temp
[root@rac1 temp]# ./Bonnie -d /home/temp/test -s 100m -m embed
File '/home/temp/test/Bonnie.1148', size: 104857600
Writing with putc()...done
Rewriting...done
Writing intelligently...done
Reading with getc()...done
Reading intelligently...done
Seeker 1...Seeker 2...Seeker 3...start 'em...done...done...done...
              -------Sequential Output-------- ---Sequential Input-- --Random--
              -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
Machine    MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU  /sec %CPU
embed     100  7252 82.7 131248 51.3 353143 100.0  7766 79.6 1362680 106.5 43996.2 99.0
[root@rac1 temp]#
--Block---
K/sec
1362680 太夸张了巴 why？

patirot

是内存里的吧，把文件加大呢？比如加大到内存的两倍或者4倍？？？

bingosek

参考一下这个，在我机器上做的：
[root@FC4 /]# hdparm -t /dev/sda

/dev/sda:
Timing buffered disk reads:   96 MB in  3.07 seconds =  31.32 MB/sec
[root@FC4 /]# hdparm -T /dev/sda

/dev/sda:
Timing cached reads:   1236 MB in  2.00 seconds = 618.09 MB/sec

bingosek

这是hdparm里两个参数的含义：
       -T     Perform  timings  of  cache  reads for benchmark and comparison purposes.  For meaningful results,
              this operation should be repeated 2-3 times on an otherwise inactive system (no other active  pro-
              cesses)  with  at  least a couple of megabytes of free memory.  This displays the speed of reading
              directly from the Linux buffer cache without disk access.   This  measurement  is  essentially  an
              indication of the throughput of the processor, cache, and memory of the system under test.  If the
              -t flag is also specified, then a correction factor based on the outcome of -T  will  be  incorpo-
              rated into the result reported for the -t operation.

       -t     Perform  timings  of  device reads for benchmark and comparison purposes.  For meaningful results,
              this operation should be repeated 2-3 times on an otherwise inactive system (no other active  pro-
              cesses)  with  at  least a couple of megabytes of free memory.  This displays the speed of reading
              through the buffer cache to the disk without any prior caching of data.  This  measurement  is  an
              indication  of  how  fast  the  drive  can  sustain sequential data reads under Linux, without any
              filesystem overhead.  To ensure accurate measurements, the buffer cache is flushed during the pro-
              cessing of -t using the BLKFLSBUF ioctl.  If the -T flag is also specified, then a correction fac-
              tor based on the outcome of -T will be incorporated into the result reported for the -t operation.