Date: Thu, 21 Nov 2019 21:52:54 +0000 From: "Keller, Jacob E" <jacob.e.keller@intel.com> To: "cem@freebsd.org" <cem@freebsd.org>, "erj@freebsd.org" <erj@freebsd.org> Cc: "src-committers@freebsd.org" <src-committers@freebsd.org>, "svn-src-head@freebsd.org" <svn-src-head@freebsd.org>, "svn-src-all@freebsd.org" <svn-src-all@freebsd.org> Subject: Re: svn commit: r354977 - in head: share/man/man3 sys/sys tests/sys/sys Message-ID: <0435131fb462d6930409ce335af25dd5a33ec2b2.camel@intel.com> In-Reply-To: <CAKdFRZgzg-1h%2Bi1O3=aaRKjGGtx=Gao_tZrz1SaQP3QgDX3x1g@mail.gmail.com> References: <201911211957.xALJvuwi054399@repo.freebsd.org> <CAG6CVpWKxfzNFC%2B94NgQ0A_Ez1Vk6v6uasXnoAKaK4aeWjDLaA@mail.gmail.com> <CAKdFRZgzg-1h%2Bi1O3=aaRKjGGtx=Gao_tZrz1SaQP3QgDX3x1g@mail.gmail.com>
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On Thu, 2019-11-21 at 13:34 -0800, Eric Joyner wrote: > On Thu, Nov 21, 2019 at 12:07 PM Conrad Meyer <cem@freebsd.org> > wrote: > > Hi Eric, > > > > On Thu, Nov 21, 2019 at 11:58 AM Eric Joyner <erj@freebsd.org> > > wrote: > > > > > > Author: erj > > > Date: Thu Nov 21 19:57:56 2019 > > > New Revision: 354977 > > > URL: https://svnweb.freebsd.org/changeset/base/354977 > > > > > > Log: > > > bitstring: add functions to find contiguous set/unset bit > > sequences > > > > > > Add bit_ffs_area_at and bit_ffc_area_at functions for searching > > a bit > > > string for a sequence of contiguous set or unset bits of at > > least the > > > specified size. > > > > > > The bit_ffc_area function will be used by the Intel ice driver > > for > > > implementing resource assignment logic using a bitstring to > > represent > > > whether or not a given index has been assigned or is currently > > free. > > > > I don't know what the ice driver is/does, so apologies if this is > > nonsensical. Would it make more sense to use vmem(9) for this > > purpose? It's a general-purpose resource allocator and can scale > > well > > with large numbers of resources / CPUs. > > > > Best, > > Conrad > Eric already added the review link for the ice driver, which we recently published. I'm currently going through review comments and preeparing an update. We use a bit string as a method of determining which index numbers have been assigned. > +Jake > > Hi Conrad, > > It doesn't seem nonsensical; this seems like it would vaguely be an > ok fit. But one issue > I find after looking at it is that it doesn't support the "scattered" > allocations that we need; for some types of > hardware queues we need to be able to group together multiple non- > sequential allocations into one single block, > and it doesn't look like we could do that without having to add > another layer on top of vmem. > I don't know much about vmem.. it might be suitable for our purposes, but it does sound like a bit overkill for what we do. I'll try to do a review of the vmem interfaces to see if it makes sense. > As well, it looks like it's kind of overbuilt for what we need; we > only need a few operations. It also seems to import > a bunch of stuff in its headers, which might complicate using it in > our unit test code. > > If you want to look at the current structure we use, you can look at > the ice_pf_qmgr.[ch] files in this Phabricator > review that introduces ice(4) to the kernel: > https://reviews.freebsd.org/D21959. > > - Eric Yes, we'd definitely appreciate review of the ice device driver code. Thanks, Jake
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