Public Service Announcement:
Случайно обнаружил, что bfq на многих ssd сводит производительность к однопоточной.
На nvme и sata Samsung’ах всё в порядке, и пропускная способность bfq растёт с количеством одновременных запросов.
А на ADATA и Transcend вот так:
Device Model: TS256GMTS400S
Serial Number: 0F109200E32506200140
Firmware Version: P1225CH4
ATA Version is: ACS-2 (minor revision not indicated)
SATA Version is: SATA 3.1, 6.0 Gb/s (current: 6.0 Gb/s)
Timing O_DIRECT disk reads: 1472 MB in 3.00 seconds = 489.96 MB/sec
/dev/sda, 256.06 GB, 1 threads:
512 B blocks: 11361.3 IO/s, 5.5 MiB/s ( 46.5 Mbit/s)
1 KiB blocks: 7762.1 IO/s, 7.6 MiB/s ( 63.6 Mbit/s)
2 KiB blocks: 4545.7 IO/s, 8.9 MiB/s ( 74.5 Mbit/s)
4 KiB blocks: 2476.4 IO/s, 9.7 MiB/s ( 81.1 Mbit/s)
8 KiB blocks: 2483.9 IO/s, 19.4 MiB/s (162.8 Mbit/s)
16 KiB blocks: 2271.1 IO/s, 35.5 MiB/s (297.7 Mbit/s)
32 KiB blocks: 1941.6 IO/s, 60.7 MiB/s (509.0 Mbit/s)
64 KiB blocks: 1360.1 IO/s, 85.0 MiB/s (713.1 Mbit/s)
128 KiB blocks: 968.5 IO/s, 121.1 MiB/s ( 1.0 Gbit/s)
/dev/sda, 256.06 GB, 4 threads:
512 B blocks: 12958.1 IO/s, 6.3 MiB/s ( 53.1 Mbit/s)
1 KiB blocks: 8832.4 IO/s, 8.6 MiB/s ( 72.4 Mbit/s)
2 KiB blocks: 4945.6 IO/s, 9.7 MiB/s ( 81.0 Mbit/s)
4 KiB blocks: 2598.6 IO/s, 10.2 MiB/s ( 85.2 Mbit/s)
8 KiB blocks: 2553.3 IO/s, 19.9 MiB/s (167.3 Mbit/s)
16 KiB blocks: 2410.9 IO/s, 37.7 MiB/s (316.0 Mbit/s)
32 KiB blocks: 2089.0 IO/s, 65.3 MiB/s (547.6 Mbit/s)
64 KiB blocks: 1463.4 IO/s, 91.5 MiB/s (767.2 Mbit/s)
128 KiB blocks: 1056.8 IO/s, 132.1 MiB/s ( 1.1 Gbit/s)
Этот же Transcend, но с mq-deadline:
/dev/sda, 256.06 GB, 4 threads:
512 B blocks: 42803.6 IO/s, 20.9 MiB/s (175.3 Mbit/s)
1 KiB blocks: 34526.3 IO/s, 33.7 MiB/s (282.8 Mbit/s)
2 KiB blocks: 24795.4 IO/s, 48.4 MiB/s (406.2 Mbit/s)
4 KiB blocks: 15848.5 IO/s, 61.9 MiB/s (519.3 Mbit/s)
8 KiB blocks: 15403.9 IO/s, 120.3 MiB/s ( 1.0 Gbit/s)
16 KiB blocks: 9705.9 IO/s, 151.7 MiB/s ( 1.3 Gbit/s)
32 KiB blocks: 5583.4 IO/s, 174.5 MiB/s ( 1.5 Gbit/s)
64 KiB blocks: 2967.9 IO/s, 185.5 MiB/s ( 1.6 Gbit/s)
128 KiB blocks: 1666.6 IO/s, 208.3 MiB/s ( 1.7 Gbit/s)
Если у вас не Самсунг, то bfq лучше не использовать.
P.S. Ещё едет терабайтный WD Blue, дополню позже.
P.P.S. Linux lin 5.10.0-0.bpo.5-amd64 #1 SMP Debian 5.10.24-1~bpo10+1 (2021-03-29) x86_64 GNU/Linux
