Re:Mkfile(8) is severely syscall limited on OS X
by mpweiher on Sunday February 12, 2017 @10:11AM
(#13628658)
Maybe I am reading it wrong, but I am not getting the 16KB optimal buffer size from that article. The summary at the end is as follows:
'In the above example it can be seen that an input block size of 128K is optimal for my particular setup.'
However, the SSD seems to be significantly slower, so the relative overhead of the syscall is going to be respectively less:
'Reading from /dev/zero and writing out to a SSD with a more optimal block size of 256K yields a throughput of 280 MB/s.'
I was getting 250MB/s with the 512 byte buffer size, although the test in the article is doing two syscalls (one read(), one write()) whereas mkfile is just doing one.
At 256KB buffer size I was already getting around 1.8GB/second writing to SSD.
'In the above example it can be seen that an input block size of 128K is optimal for my particular setup.'
However, the SSD seems to be significantly slower, so the relative overhead of the syscall is going to be respectively less:
'Reading from /dev/zero and writing out to a SSD with a more optimal block size of 256K yields a throughput of 280 MB/s.'
I was getting 250MB/s with the 512 byte buffer size, although the test in the article is doing two syscalls (one read(), one write()) whereas mkfile is just doing one.
At 256KB buffer size I was already getting around 1.8GB/second writing to SSD.