Date: Tue, 21 Aug 2018 17:35:12 -0700 From: John-Mark Gurney <jmg@funkthat.com> To: Support SimpleRezo <simplerezo@gmail.com> Cc: freebsd-virtualization@freebsd.org Subject: Re: [HyperV-2016] urandom performance issue... Message-ID: <20180822003512.GI97145@funkthat.com> In-Reply-To: <CALVu1vZ3iSFDt60mLVie_17rejNeXggjDOGdY7HuYeRGmMxM=w@mail.gmail.com> References: <CALVu1vZ3iSFDt60mLVie_17rejNeXggjDOGdY7HuYeRGmMxM=w@mail.gmail.com>
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Support SimpleRezo wrote this message on Tue, Aug 21, 2018 at 19:06 +0200: > I was figuring a performance issue of a FreeBSD on HyperV, after: > - moving it from an Hyper-V 2012 host to a Hyper-V 2016 > - updating to FreeBSD 11.2 (custom kernel, but same issue with GENERIC) > After loosing some times because i was thinking about hardware issue (disk > controller was my first thought...) and testing with "dd > if=/dev/urandom"... I discovered this... > > I ran the following test... and quite surprised by the speed result! > $ dd if=/dev/urandom of=/dev/null bs=10M count=3 > 3+0 records in > 3+0 records out > 31457280 bytes transferred in 27.960431 secs (1125064 bytes/sec) > The test was also sometimes "freezing" the Hyper-V host! > > Looking into "dmesg" i have found this: > random: registering fast source Intel Secure Key RNG > random: fast provider: "Intel Secure Key RNG" > > So I rebuilt my KERNEL without "rdrand_rng" (didn't find another way to > disable it...)... and performances went back to normal! > > I think this issue should documented on https://wiki.freebsd.org/HyperV ! This is likely the same issue as: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=230808 If you're having troubles w/ the host freezing, this should probably still be investigated as even w/ the excessive locking, it should never freeze. -- John-Mark Gurney Voice: +1 415 225 5579 "All that I will do, has been done, All that I have, has not."
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