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Date:      Fri, 15 May 2020 14:45:05 +0000
From:      bugzilla-noreply@freebsd.org
To:        usb@FreeBSD.org
Subject:   [Bug 244356] Writing to a USB 3.0 stick is very slow
Message-ID:  <bug-244356-19105-ChIbLgeXOG@https.bugs.freebsd.org/bugzilla/>
In-Reply-To: <bug-244356-19105@https.bugs.freebsd.org/bugzilla/>
References:  <bug-244356-19105@https.bugs.freebsd.org/bugzilla/>

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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D244356

--- Comment #45 from Olivier Certner <olivier.freebsd@free.fr> ---
Hi S=C3=A9bastien and Hans,

Contrary to what I recalled (or something changed since then), SD_64G and
SD_128G indeed seem bad. I did some tests in order to verify behavior on ot=
her
OSes, and both sticks exhibit the same transfer pattern on recent Linux and
MacOS X machines, i.e., usually 2 or 3s of decent bandwidth, followed by 2 =
or
3s without transfer and some "probe" transaction, often repeated. So I'm si=
mply
going to RMA them.

The only difference with other OSes is that apparent bandwidth is somewhat
higher, though still low (USB 2.0 or less speeds). KB/t appears to be
frequently near 1024, where it is around 128 on FreeBSD (but then with high=
er
tps); the overhead of smaller transactions may explain the difference.

Will test KT_32G later to see how it fares.

Hans, thanks for `usbtest`.

A few question: In `usbtest`, does <Random> for the I/O size has any alignm=
ent
constraint on the size (like multiples of some power of 2, or only powers of
2)? And what about <Increasing>? In umass, is it possible to have longer
transaction then 128KB?

Thanks.

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