Date: Thu, 5 Nov 2020 16:44:17 +0100 From: Gary Jennejohn <gljennjohn@gmail.com> To: Hans Petter Selasky <hps@selasky.org> Cc: vermaden <vermaden@interia.pl>, freebsd-usb@freebsd.org Subject: Re: mSATA SSD over USB adater: 300MB/s @ Linux versus 100MB/s @ FreeBSD Message-ID: <20201105154417.6abdb0d2@ernst.home> In-Reply-To: <181b2eab-79f4-9bd2-45dc-0be3dd3aa9f4@selasky.org> References: <bfpxcgtgpqkwctqlhswo@dwvh> <uegzkiqfagbtouldiwpf@svwv> <20201105092733.30d6d2a9@ernst.home> <dkewsdnnstfpatmrwaqk@yesp> <181b2eab-79f4-9bd2-45dc-0be3dd3aa9f4@selasky.org>
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On Thu, 5 Nov 2020 15:26:35 +0100 Hans Petter Selasky <hps@selasky.org> wrote: > On 2020-11-05 14:05, vermaden wrote: > > So we should slow down Linux so FreeBSD can keep up?:) > > Please also keep in mind that Linux has a data cache on /dev/sdb, > while FreeBSD always goes to the device! > > Try to disable caching in Linux first. > This is true. Linux will happily cache megabytes of data, which makes the whole transfer seem to be faster. I've observed this behavior in Linux myself. dd claims to be finished but then it can take minutes before the data actually land on the target disk. This is easily seen with e.g. gkrellm2. -- Gary Jennejohn
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