Date: Wed, 17 Aug 2016 11:12:38 +0200 From: Roger Pau =?iso-8859-1?Q?Monn=E9?= <roger.pau@citrix.com> To: <rainer@ultra-secure.de> Cc: <freebsd-xen@freebsd.org>, <owner-freebsd-xen@freebsd.org> Subject: Re: Is it me or is FreeBSD slower on Xen than Linux? Message-ID: <20160817091229.hm5a66ftwnfoj7vx@mac> In-Reply-To: <599395934f751784b1f842ed3c8f879c@ultra-secure.de> References: <20160816110759.6xlvxikw3tziahfd@mac> <c3a3a7da26cd1a6a114c03e823926272@ultra-secure.de> <20160816132938.d2i4u2y3scpzi2et@mac> <00D22384-BAA7-42E4-A486-4BE07562D011@sarenet.es> <8521aebaa093bcefe5956a71fd879140@ultra-secure.de> <872C5626-F58D-4F84-92AC-88B7352D1DDF@sarenet.es> <c6bdef83f2370173c067820565bf933e@ultra-secure.de> <20160816141826.56mxsgx6e7rynxqg@mac> <cff064d12c783cc6eebba4b56f063ba7@ultra-secure.de> <599395934f751784b1f842ed3c8f879c@ultra-secure.de>
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On Wed, Aug 17, 2016 at 10:19:05AM +0200, rainer@ultra-secure.de wrote: > Am 2016-08-16 16:24, schrieb rainer@ultra-secure.de: > > Am 2016-08-16 16:18, schrieb Roger Pau Monné: > > > > > I'm not saying it's not possible, but are you sure this slowdown is > > > caused > > > by the disk? It's certainly a possibility, but I would like to make > > > sure > > > it's caused by that before jumping into conclusions. > > > > > > Can you load the full database in RAM and perform the same test. > > > TBH, I > > > don't use MariaDB, so I'm not sure what's the best way to achieve > > > this, but > > > a quick search on google shows there are multiple ways. In any case, > > > make > > > sure with iostat that the database is not read from the disk. > > > > I'll try to do some disk-benchmarks, when I can attach some bigger > > disks. > > on Ubuntu 14 with HVM: > > dc3dd wipe=/dev/xvdc > > dc3dd 7.1.614 started at 2016-08-17 09:38:17 +0200 > compiled options: > command line: dc3dd wipe=/dev/xvdc > device size: 104857600 sectors (probed) > sector size: 512 bytes (probed) > 53687091200 bytes (50 G) copied (100%), 464.642 s, 110 M/s > > input results for pattern `00': > 104857600 sectors in > > output results for device `/dev/xvdc': > 104857600 sectors out > > dc3dd completed at 2016-08-17 09:46:01 +0200 > > > On FreeBSD 10.3-RELEASE-p6 with HVM: > > Aug 17 09:57:52 bla-prod kernel: xbd4: 51200MB <Virtual Block Device> at > device/vbd/51776 on xenbusb_front0 > Aug 17 09:57:52 bla-prod kernel: xbd4: features: write_barrier > Aug 17 09:57:52 bla-prod kernel: xbd4: synchronize cache commands enabled. > > dc3dd wipe=/dev/xbd4 > > and it's showing 8.something MB/s > > Is this normal? No, I don't think so, this is what I get using a slow USB 2.0 disk as the backend: (on Dom0 I get something between 70-80M/s, so there isn't much difference). # dc3dd wipe=/dev/ada1 dc3dd 7.2.641 started at 2016-08-17 09:03:26 +0000 compiled options: command line: dc3dd wipe=/dev/ada1 device size: 2097152 sectors (probed), 1,073,741,824 bytes sector size: 512 bytes (probed) 1073741824 bytes ( 1 G ) copied ( 100% ), 16 s, 65 M/s input results for pattern `00': 2097152 sectors in output results for device `/dev/ada1': 2097152 sectors out dc3dd completed at 2016-08-17 09:03:42 +0000 > What may I be doing wrong? TBH it's hard to tell, I don't know of any option that could cause this disk performance degradation. Do you also have ada* devices apart from the xbd* ones? I don't think it's going to make any difference, but could you try with the ada* block devices instead? Roger.
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