Date: Fri, 30 Oct 2020 16:42:39 +0100 From: Mateusz Guzik <mjguzik@gmail.com> To: Konstantin Belousov <kostikbel@gmail.com> Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r367165 - head/sys/fs/tmpfs Message-ID: <CAGudoHFzaatrWLx4-q3FA=G8wMFkjvPj5kbdgH=7hPyzP-nfJQ@mail.gmail.com> In-Reply-To: <20201030143851.GE2654@kib.kiev.ua> References: <202010301407.09UE7Phw060731@repo.freebsd.org> <CAGudoHGBMFoeOKwZWq2%2B1xC9924Xi2AEt4a1zYgwa_EA3HzAkA@mail.gmail.com> <20201030143851.GE2654@kib.kiev.ua>
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On 10/30/20, Konstantin Belousov <kostikbel@gmail.com> wrote: > On Fri, Oct 30, 2020 at 03:08:32PM +0100, Mateusz Guzik wrote: >> On 10/30/20, Mateusz Guzik <mjg@freebsd.org> wrote: >> > Author: mjg >> > Date: Fri Oct 30 14:07:25 2020 >> > New Revision: 367165 >> > URL: https://svnweb.freebsd.org/changeset/base/367165 >> > >> > Log: >> > tmpfs: change tmpfs dirent zone into a malloc type >> > >> > It is 64 bytes. >> > >> >> Right now malloc has only power-of-2 zones but I'm looking into >> changing that. The allocator itself trivially extends to multiply of >> 16, but stat collection needs reworking. > > Either commit message or follow-up do not explain why stopping using > zone for dirents is useful. Intuition says exactly reverse, dirents > on tmpfs are allocation-intensive typically. > Off hand the only reasons to use a dedicated zones that I see are: - use of any of the routines on object creation/destruction - non-standard flags like NOFREE - SMR - high expected allocated count with sizes poorly fit for malloc Since malloc itself is implemented on top of zones, the difference before/after the patch is that now it can re-use the pre-existing 64 byte buckets instead of creating its own copy. The above follow up was to address potential comments about the size changing from 64 -- with better malloc granularity this wont be a big deal. Also note tmpfs already uses malloc to store names. If anything in my opinion the kernel has unnecessary zones (like the vnode poll one I patched prior to this). -- Mateusz Guzik <mjguzik gmail.com>
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