Date: Thu, 26 Jun 2014 01:12:29 +0800 From: Julian Elischer <julian@freebsd.org> To: Alfred Perlstein <alfred@freebsd.org>, attilio@FreeBSD.org, Gleb Smirnoff <glebius@freebsd.org> Cc: Alan Cox <alc@freebsd.org>, "svn-src-head@freebsd.org" <svn-src-head@freebsd.org>, "svn-src-all@freebsd.org" <svn-src-all@freebsd.org>, =?UTF-8?B?Um9nZXIgUGF1IE1vbm7DqQ==?= <royger@freebsd.org>, "src-committers@freebsd.org" <src-committers@freebsd.org> Subject: Re: svn commit: r267858 - in head/sys/dev: virtio/balloon xen/balloon Message-ID: <53AB02FD.20502@freebsd.org> In-Reply-To: <53AAE7D0.2090508@freebsd.org> References: <201406250951.s5P9p8YR017159@svn.freebsd.org> <CAJ-FndD4M8QkejyTv4R_9qoThqvFinYbHP4YSby6mQS9EKSYPA@mail.gmail.com> <20140625120932.GM28199@FreeBSD.org> <CAJ-FndAHV1sHOreWThZoVr-bbQSXv9=QPHX9=QZNQmkGFUTRMw@mail.gmail.com> <53AAE7D0.2090508@freebsd.org>
next in thread | previous in thread | raw e-mail | index | archive | help
On 6/25/14, 11:16 PM, Alfred Perlstein wrote: > On 6/25/14 5:41 AM, Attilio Rao wrote: >> On Wed, Jun 25, 2014 at 2:09 PM, Gleb Smirnoff >> <glebius@freebsd.org> wrote: >>> On Wed, Jun 25, 2014 at 01:58:29PM +0200, Attilio Rao wrote: >>> A> > Log: >>> A> > xen/virtio: fix balloon drivers to not mark pages as WIRED >>> A> > >>> A> > Prevent the Xen and VirtIO balloon drivers from marking >>> pages as >>> A> > wired. This prevents them from increasing the system wired >>> page count, >>> A> > which can lead to mlock failing because of hitting the >>> limit in >>> A> > vm.max_wired. >>> A> >>> A> This change is conceptually wrong. >>> A> The pages balloon is allocating are unmanaged and they should >>> be wired >>> A> by definition. Alan and I are considering enforcing this >>> (mandatory >>> A> wired pages for unmanaged pages allocation) directly in the KPI. >>> A> This in practice just seem an artifact to deal with scarce wired >>> A> memory limit. I suggest that for the XEN case this limit gets >>> bumped >>> A> rather relying on similar type of hacks. >>> >>> Proper limit would be to count pages wired by userland via mlock(2) >>> and enforce limit only on those pages. Pages wired by kernel should >>> be either unlimited or controled by a separate limit. >> FWIW, I mostly agree with this. I think that the kernel and userland >> limits should be split apart. But for the time being, rising the limit >> is better. >> >> Attilio >> >> > Can you explain? I would think that if you were designing some kind > of embedded device you would want to know exactly how much locked > pages there are overall, not just in userland. > > Meaning you would not want to overcommit and have too many locked > pages due to kernel+user. > > Perhaps that needs an API as well? these pages are the VM equivalent of memory pages that were 'found to be flaky and taken out of service" I think "wired" is a bad description for those.
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?53AB02FD.20502>