FAQ: how come write is faster than read?
Posted: Sat May 23, 2020 6:51 pm
i'm guessing the write cache on the storage device is contributing to this behavior. to be confirmed...
fio exhibits the same issue.
APPLE SSD SM0512F:
fio exhibits the same issue.
APPLE SSD SM0512F:
- Read: 26.8MB/s
- Write: 102MB/s
Code: Select all
$ fio --name=test --ioengine=posixaio --direct=1 --gtod_reduce=1 --bs=4k --iodepth=1 --size=500M --readwrite=randread
...
Run status group 0 (all jobs):
READ: bw=25.6MiB/s (26.8MB/s), 25.6MiB/s-25.6MiB/s (26.8MB/s-26.8MB/s), io=500MiB (524MB), run=19542-19542msec
Code: Select all
$ fio --name=test --ioengine=posixaio --direct=1 --gtod_reduce=1 --bs=4k --iodepth=1 --size=500M --readwrite=randwrite
...
Run status group 0 (all jobs):
WRITE: bw=97.5MiB/s (102MB/s), 97.5MiB/s-97.5MiB/s (102MB/s-102MB/s), io=500MiB (524MB), run=5130-5130msec