Date: Sat, 2 Dec 2017 17:21:27 -0800 From: "K. Macy" <kmacy@freebsd.org> To: Allan Jude <allanjude@freebsd.org> Cc: "freebsd-virtualization@freebsd.org" <freebsd-virtualization@freebsd.org> Subject: Re: bhyve uses all available memory during IO-intensive operations Message-ID: <CAHM0Q_P9G8CND3XrfpNoVRoNws%2BMgR02jpJRY3BQpY93Eo5s0Q@mail.gmail.com> In-Reply-To: <11e6e55d-9802-c9fc-859c-37c026eaba2b@freebsd.org> References: <F4E35CB9-30F9-4C63-B4CC-F8ADC9947E3C@ebureau.com> <CAHM0Q_MPNEBq=J9yJADhzA96nKvdgEiFESV-0Y9JB5mewfGspQ@mail.gmail.com> <59DFCE5F-029F-4585-B0BA-8FABC43357F2@ebureau.com> <11e6e55d-9802-c9fc-859c-37c026eaba2b@freebsd.org>
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On Sat, Dec 2, 2017 at 5:16 PM, Allan Jude <allanjude@freebsd.org> wrote: > On 12/02/2017 00:23, Dustin Wenz wrote: >> I have noticed significant storage amplification for my zvols; that coul= d very well be the reason. I would like to know more about why it happens. >> >> Since the volblocksize is 512 bytes, I certainly expect extra cpu overhe= ad (and maybe an extra 1k or so worth of checksums for each 128k block in t= he vm), but how do you get a 10X expansion in stored data? >> >> What is the recommended zvol block size for a FreeBSD/ZFS guest? Perhaps= 4k, to match the most common mass storage sector size? >> >> - .Dustin >> >>> On Dec 1, 2017, at 9:18 PM, K. Macy <kmacy@freebsd.org> wrote: >>> >>> One thing to watch out for with chyves if your virtual disk is more >>> than 20G is the fact that it uses 512 byte blocks for the zvols it >>> creates. I ended up using up 1.4TB only half filling up a 250G zvol. >>> Chyves is quick and easy, but it's not exactly production ready. >>> >>> -M >>> >>> >>> >>>> On Thu, Nov 30, 2017 at 3:15 PM, Dustin Wenz <dustinwenz@ebureau.com> = wrote: >>>> I'm using chyves on FreeBSD 11.1 RELEASE to manage a few VMs (guest OS= is also FreeBSD 11.1). Their sole purpose is to house some medium-sized Po= stgres databases (100-200GB). The host system has 64GB of real memory and 1= 12GB of swap. I have configured each guest to only use 16GB of memory, yet = while doing my initial database imports in the VMs, bhyve will quickly grow= to use all available system memory and then be killed by the kernel: >>>> >>>> kernel: swap_pager: I/O error - pageout failed; blkno 1735,size= 4096, error 12 >>>> kernel: swap_pager: I/O error - pageout failed; blkno 1610,size= 4096, error 12 >>>> kernel: swap_pager: I/O error - pageout failed; blkno 1763,size= 4096, error 12 >>>> kernel: pid 41123 (bhyve), uid 0, was killed: out of swap space >>>> >>>> The OOM condition seems related to doing moderate IO within the VM, th= ough nothing within the VM itself shows high memory usage. This is the chyv= es config for one of them: >>>> >>>> bargs -A -H -P -S >>>> bhyve_disk_type virtio-blk >>>> bhyve_net_type virtio-net >>>> bhyveload_flags >>>> chyves_guest_version 0300 >>>> cpu 4 >>>> creation Created on Mon Oct 23 16:17:04 CDT 2= 017 by chyves v0.2.0 2016/09/11 using __create() >>>> loader bhyveload >>>> net_ifaces tap51 >>>> os default >>>> ram 16G >>>> rcboot 0 >>>> revert_to_snapshot >>>> revert_to_snapshot_method off >>>> serial nmdm51 >>>> template no >>>> uuid 8495a130-b837-11e7-b092-0025909a8b56 >>>> >>>> >>>> I've also tried using different bhyve_disk_types, with no improvement.= How is it that bhyve can use far more memory that I'm specifying? >>>> >>>> - .Dustin >> _______________________________________________ >> freebsd-virtualization@freebsd.org mailing list >> https://lists.freebsd.org/mailman/listinfo/freebsd-virtualization >> To unsubscribe, send any mail to "freebsd-virtualization-unsubscribe@fre= ebsd.org" >> > > Storage amplification usually has to do with ZFS RAID-Z padding. If your > ZVOL block size does not make sense with your disk sector size, and > RAID-Z level, you can get pretty silly numbers. That's not what I'm talking about here. If your volblocksize is too small you end up using (vastly) more space for indirect blocks than data blocks. -M
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