Slow USB transfers

Support
26

You are right after my tests. The cached transfer is a trick.

sudo mount -t exfat -o async,uid=1000,gid=1000 /dev/sda1 /mnt/

With cache:
Result:

===Start===
RAM cache:
procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu-----
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
 2  0      0 18555080  86648 6537648    0    0  3640  6544 4136    3  1  1 97  2  0

===1.repeat===
Rsync your data:
video_test_2GB.mkv
  2.108.896.285 100%  674,21MB/s    0:00:02 (xfr#1, to-chk=0/1)

===End===
RAM cache:
procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu-----
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
 1  0      0 16010948  86648 9024236    0    0  3632  6530 4149    3  1  1 97  2  0

I disabled cache:

echo 16777216 > /sys/block/sda/bdi/max_bytes
echo 1 > /sys/block/sda/bdi/strict_limit
Result:

===Start===
RAM cache:
procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu-----
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
 1  0      0 18078912  94088 6702120    0    0  2958  6543 4306    3  1  1 97  1  0

===1.repeat===
Rsync your data:
video_test_2GB.mkv
  2.108.896.285 100%   37,40MB/s    0:00:53 (xfr#1, to-chk=0/1)

===End===
RAM cache:
procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu-----
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
 1  0      0 15544208  94204 9188888    0    0  2870  7507 4267    3  1  1 97  2  0
1 Like