Navíc i disk na Gen3x4 dával na tom HW přes dd jen cca 1,3GB/s (Gen3x1 cca 650MB/s)
jeste k tomu dd, ted jsem zkousel nvme disk v S920 (AMD GX-424CC) s pcie gen2 4x slotem
discardnul ho, udelal 64Gb ext4 partition, namountoval pod /mnt
fio test hlasi ccca 1.5GB/s
ubuntu@ubuntu:~$ fio --filename=/mnt/test.bin --direct=1 --rw=read --ioengine=libaio --bs=2m --iodepth=64 --size=10G --numjobs=1 --runtime=60 --time_base=1 --group_reporting --name=test-seq-read
test-seq-read: (g=0): rw=read, bs=(R) 2048KiB-2048KiB, (W) 2048KiB-2048KiB, (T) 2048KiB-2048KiB, ioengine=libaio, iodepth=64
fio-3.28
Starting 1 process
Jobs: 1 (f=1): [R(1)][100.0%][r=1568MiB/s][r=783 IOPS][eta 00m:00s]
test-seq-read: (groupid=0, jobs=1): err= 0: pid=5665: Sat Jan 11 12:11:35 2025
read: IOPS=749, BW=1500MiB/s (1573MB/s)(88.0GiB/60082msec)
slat (usec): min=169, max=2759, avg=419.99, stdev=60.66
clat (msec): min=15, max=606, avg=82.34, stdev=20.99
lat (msec): min=15, max=607, avg=82.76, stdev=20.99
clat percentiles (msec):
| 1.00th=[ 57], 5.00th=[ 82], 10.00th=[ 82], 20.00th=[ 82],
| 30.00th=[ 82], 40.00th=[ 82], 50.00th=[ 82], 60.00th=[ 82],
| 70.00th=[ 82], 80.00th=[ 82], 90.00th=[ 82], 95.00th=[ 84],
| 99.00th=[ 113], 99.50th=[ 123], 99.90th=[ 609], 99.95th=[ 609],
| 99.99th=[ 609]
bw ( MiB/s): min= 464, max= 1572, per=100.00%, avg=1538.33, stdev=150.03, samples=117
iops : min= 232, max= 786, avg=769.18, stdev=75.02, samples=117
lat (msec) : 20=0.01%, 50=0.69%, 100=97.35%, 250=1.81%, 750=0.14%
cpu : usr=1.09%, sys=38.53%, ctx=45151, majf=1, minf=32780
IO depths : 1=0.1%, 2=0.1%, 4=0.1%, 8=0.1%, 16=0.1%, 32=0.1%, >=64=99.9%
submit : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
complete : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.1%, >=64=0.0%
issued rwts: total=45061,0,0,0 short=0,0,0,0 dropped=0,0,0,0
latency : target=0, window=0, percentile=100.00%, depth=64
Run status group 0 (all jobs):
READ: bw=1500MiB/s (1573MB/s), 1500MiB/s-1500MiB/s (1573MB/s-1573MB/s), io=88.0GiB (94.5GB), run=60082-60082msec
Disk stats (read/write):
nvme0n1: ios=372626/81, merge=9147/8, ticks=30456089/8956, in_queue=30465489, util=97.26%
dd s iflag=direct cca 1.2GB/s
ubuntu@ubuntu:~$ sudo dd if=/mnt/test.bin of=/dev/null bs=1M iflag=direct
10240+0 records in
10240+0 records out
10737418240 bytes (11 GB, 10 GiB) copied, 9.00009 s, 1.2 GB/s
ubuntu@ubuntu:~$ sudo dd if=/mnt/test.bin of=/dev/null bs=1M iflag=direct
10240+0 records in
10240+0 records out
10737418240 bytes (11 GB, 10 GiB) copied, 9.04387 s, 1.2 GB/s
dd bez direct flagu cca 850MB/s
ubuntu@ubuntu:~$ echo 3 | sudo tee /proc/sys/vm/drop_caches ; sudo dd if=/mnt/test.bin of=/dev/null bs=1M
3
10240+0 records in
10240+0 records out
10737418240 bytes (11 GB, 10 GiB) copied, 12.4712 s, 861 MB/s
ubuntu@ubuntu:~$ echo 3 | sudo tee /proc/sys/vm/drop_caches ; sudo dd if=/mnt/test.bin of=/dev/null bs=1M
3
10240+0 records in
10240+0 records out
10737418240 bytes (11 GB, 10 GiB) copied, 12.6382 s, 850 MB/s
ubuntu@ubuntu:~$ echo 3 | sudo tee /proc/sys/vm/drop_caches ; sudo dd if=/mnt/test.bin of=/dev/null bs=1M
3
10240+0 records in
10240+0 records out
10737418240 bytes (11 GB, 10 GiB) copied, 12.5512 s, 855 MB/s