Date: Wed, 05 Sep 2018 16:29:43 +0000 From: bugzilla-noreply@freebsd.org To: freebsd-arm@FreeBSD.org Subject: [Bug 231178] Very slow IO with small block size Message-ID: <bug-231178-7@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D231178 Bug ID: 231178 Summary: Very slow IO with small block size Product: Base System Version: CURRENT Hardware: arm64 OS: Any Status: New Severity: Affects Only Me Priority: --- Component: arm Assignee: freebsd-arm@FreeBSD.org Reporter: robert.david.public@gmail.com On raspberry pi3 aarch64, I have noticed very slow IO on any type of storage device (USB,mmc) when the block size is slow. Example execution of dd shows huge difference (>10x) pi-backup ~ # dd if=3D/dev/mmcsd0 of=3D/dev/zero bs=3D1M 3781+1 records in 3781+1 records out 3965190144 bytes transferred in 226.929478 secs (17473226 bytes/sec) pi-backup ~ # dd if=3D/dev/mmcsd0 of=3D/dev/zero bs=3D512 ^C981585+0 records in 981585+0 records out 502571520 bytes transferred in 375.254570 secs (1339282 bytes/sec) (Note I have stopped that, because it would take >half hour to read 4GB sd card) Similar results can be seen on USB hdd. This practically make speed of any = fs (UFS/ZFS) <1MB/s. For comparison this is results from Linux 4.14 rpi64 ~ # dd if=3D/dev/mmcblk0 of=3D/dev/zero bs=3D512 7744512+0 records in 7744512+0 records out 3965190144 bytes (4.0 GB, 3.7 GiB) copied, 178.385 s, 22.2 MB/s rpi64 ~ # dd if=3D/dev/mmcblk0 of=3D/dev/zero bs=3D1M 3781+1 records in 3781+1 records out 3965190144 bytes (4.0 GB, 3.7 GiB) copied, 168.359 s, 23.6 MB/s I do not expect FreeBSD be easily on par with Linux, but on the other side there seems to be huge bottleneck/contention somewhere. Since it is not driver specific (USB/mmc), I expect something in core kernel not optimized yet. --=20 You are receiving this mail because: You are the assignee for the bug.=
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