Date: Tue, 28 May 2019 15:52:11 +0300 From: Andriy Gapon <avg@FreeBSD.org> To: Warner Losh <imp@bsdimp.com>, Matthew Seaman <matthew@freebsd.org> Cc: "freebsd-hackers@freebsd.org" <freebsd-hackers@freebsd.org>, Colin Percival <cperciva@freebsd.org>, Alex Dupre <ale@freebsd.org>, Jonathan Anderson <jonathan@freebsd.org> Subject: Re: Amazon AMIs Message-ID: <74ed9ad5-58d9-db02-2e20-b053ba5eeb87@FreeBSD.org> In-Reply-To: <CANCZdfp0ZWe11jXw_xnPi8G2QhyEeBTOcN_ks=sqJCqDjDYcQg@mail.gmail.com> References: <f002c020-1e63-c12f-456e-e20f8546a701@FreeBSD.org> <8a139c9c-b98b-4a54-1d7c-0ea1e3dc7a72@freebsd.org> <53a0bd68-a6ba-e8ad-4af2-abeb22e92c03@FreeBSD.org> <E396A0C7-F939-48A1-9B57-D643806B303B@FreeBSD.org> <f51b836f-6a40-9be3-425a-e1afd301507b@FreeBSD.org> <CANCZdfp0ZWe11jXw_xnPi8G2QhyEeBTOcN_ks=sqJCqDjDYcQg@mail.gmail.com>
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On 21/02/2019 18:17, Warner Losh wrote: > On Thu, Feb 21, 2019 at 1:02 AM Matthew Seaman <matthew@freebsd.org> wrote: > >> On 20/02/2019 22:32, Jonathan Anderson wrote: >>> On 20 Feb 2019, at 18:50, Alex Dupre wrote: >>> >>>> Colin Percival wrote: >>>>> Last time I looked at this, we weren't handling hotplug/hotunplug of >>>>> "NVMe" >>>>> disks properly on the m5/c5/etc. instances. I opted to recommend the >>>>> instance >>>>> which completely works rather than the one with slightly better >>>>> performance... >>>> >>>> It does happen only on a few instances, but I get some freezes on new t3 >>>> machines: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=235856 >>>> >>>> They are indeed cheaper and more performant, but not 100% reliable in >>>> every workload. >>> >>> https://www.xkcd.com/937 ? >>> >> >> Yes, indeed. That's a very good reason not to recommend the newest and >> shiniest. I haven't seen any problems so far, but then again it's only >> been a day or so and we haven't got into the full testing regime quite >> yet. I'll let you know if we do run into problems. >> >> Is there work on hot-plug NVMe going on? ISTR jmg@ mentioning hotplug >> PCI at the dev summit at Stockholm EuroBSDCon, but not much since then. >> > > It's hot-unplug that doesn't work quite right. Hotplug works, I believe, if > you have PCI_HP in your kernel, I believe. > > What's needed is about a solid week of cleanup and testing in this area, > however. I am not sure about the context of the latest question... whether it was about NVMe hot-plug on real modern hardware or whether it was still about AWS. In the latter case, as Colin pointed out earlier[*], PCI_HP would not help at all, because the emulated bridge is not a PCIe bridge. It seems that they use a mechanism based on an older specification, PCI Standard Hot-Plug Controller and Subsystem Specification. I believe that FreeBSD never implemented it. [*] http://www.daemonology.net/blog/2017-11-17-FreeBSD-EC2-C5-instances.html -- Andriy Gapon
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