diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/ioblksize.h | 42 |
1 files changed, 24 insertions, 18 deletions
diff --git a/src/ioblksize.h b/src/ioblksize.h index dfdaff4ae..276d38fe6 100644 --- a/src/ioblksize.h +++ b/src/ioblksize.h @@ -20,7 +20,7 @@ #include "stat-size.h" -/* As of Jul 2011, 64KiB is determined to be the minimium +/* As of May 2014, 128KiB is determined to be the minimium blksize to best minimize system call overhead. This can be tested with this script: @@ -33,23 +33,29 @@ done With the results shown for these systems: - system-1 = 1.7GHz pentium-m with 400MHz DDR2 RAM, arch=i686 - system-2 = 2.1GHz i3-2310M with 1333MHz DDR3 RAM, arch=x86_64 - system-3 = 3.2GHz i7-970 with 1333MHz DDR3, arch=x86_64 + system #1: 1.7GHz pentium-m with 400MHz DDR2 RAM, arch=i686 + system #2: 2.1GHz i3-2310M with 1333MHz DDR3 RAM, arch=x86_64 + system #3: 3.2GHz i7-970 with 1333MHz DDR3, arch=x86_64 + system #4: 2.20GHz Xeon E5-2660 with 1333MHz DDR3, arch=x86_64 + system #5: 2.30GHz i7-3615QM with 1600MHz DDR3, arch=x86_64 + system #6: 1.30GHz i5-4250U with 1-channel 1600MHz DDR3, arch=x86_64 + system #7: 3.55GHz IBM,8231-E2B with 1066MHz DDR3, POWER7 revision 2.1 + + per-system transfer rate (GB/s) + blksize #1 #2 #3 #4 #5 #6 #7 + ------------------------------------------------------------------------ + 1024 .73 1.7 2.6 .64 1.0 2.5 1.3 + 2048 1.3 3.0 4.4 1.2 2.0 4.4 2.5 + 4096 2.4 5.1 6.5 2.3 3.7 7.4 4.8 + 8192 3.5 7.3 8.5 4.0 6.0 10.4 9.2 + 16384 3.9 9.4 10.1 6.3 8.3 13.3 16.8 + 32768 5.2 9.9 11.1 8.1 10.7 13.2 28.0 + 65536 5.3 11.2 12.0 10.6 12.8 16.1 41.4 + 131072 5.5 11.8 12.3 12.1 14.0 16.7 54.8 + 262144 5.7 11.6 12.5 12.3 14.7 16.4 40.0 + 524288 5.7 11.4 12.5 12.1 14.7 15.5 34.5 + 1048576 5.8 11.4 12.6 12.2 14.9 15.7 36.5 - blksize system-1 system-2 system-3 - --------------------------------------- - 1024 734 MB/s 1.7 GB/s 2.6 GB/s - 2048 1.3 GB/s 3.0 GB/s 4.4 GB/s - 4096 2.4 GB/s 5.1 GB/s 6.5 GB/s - 8192 3.5 GB/s 7.3 GB/s 8.5 GB/s - 16384 3.9 GB/s 9.4 GB/s 10.1 GB/s - 32768 5.2 GB/s 9.9 GB/s 11.1 GB/s - 65536 5.3 GB/s 11.2 GB/s 12.0 GB/s - 131072 5.5 GB/s 11.8 GB/s 12.3 GB/s - 262144 5.7 GB/s 11.6 GB/s 12.5 GB/s - 524288 5.7 GB/s 11.4 GB/s 12.5 GB/s - 1048576 5.8 GB/s 11.4 GB/s 12.6 GB/s Note that this is to minimize system call overhead. Other values may be appropriate to minimize file system @@ -64,7 +70,7 @@ In the future we could use the above method if available and default to io_blksize() if not. */ -enum { IO_BUFSIZE = 64*1024 }; +enum { IO_BUFSIZE = 128*1024 }; static inline size_t io_blksize (struct stat sb) { |