Date: Sat, 8 Aug 2020 03:39:15 +0200 From: Mateusz Guzik <mjguzik@gmail.com> To: Alan Somers <asomers@freebsd.org> Cc: src-committers <src-committers@freebsd.org>, svn-src-all <svn-src-all@freebsd.org>, svn-src-head <svn-src-head@freebsd.org> Subject: Re: svn commit: r364044 - in head: share/man/man9 sys/compat/linuxkpi/common/src sys/kern sys/security/audit sys/sys Message-ID: <CAGudoHFwQtcftxGfVCSsM9GPXsFR=Pt3iWQQphLoFM7WGmm%2BbA@mail.gmail.com> In-Reply-To: <CAOtMX2iOJ_zZV84RrxD9BHokZR3nWiiZ8VV%2BU9bscZPYogvOGA@mail.gmail.com> References: <202008072306.077N6fjP084661@repo.freebsd.org> <CAOtMX2iOJ_zZV84RrxD9BHokZR3nWiiZ8VV%2BU9bscZPYogvOGA@mail.gmail.com>
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tmpfs_getattr fills > 100 bytes worth of data into struct vattr, which then has to be converted to struct stat format. The conversion happens to copy some of it as it is and branch on other stuff. tmpfs_stat elides the entire process. On 8/8/20, Alan Somers <asomers@freebsd.org> wrote: > On Fri, Aug 7, 2020 at 5:06 PM Mateusz Guzik <mjg@freebsd.org> wrote: > >> Author: mjg >> Date: Fri Aug 7 23:06:40 2020 >> New Revision: 364044 >> URL: https://svnweb.freebsd.org/changeset/base/364044 >> >> Log: >> vfs: add VOP_STAT >> >> The current scheme of calling VOP_GETATTR adds avoidable overhead. >> >> An example with tmpfs doing fstat (ops/s): >> before: 7488958 >> after: 7913833 >> >> Reviewed by: kib (previous version) >> Differential Revision: https://reviews.freebsd.org/D25910 >> >> Modified: >> head/share/man/man9/Makefile >> head/share/man/man9/VOP_ATTRIB.9 >> head/sys/compat/linuxkpi/common/src/linux_compat.c >> head/sys/kern/vfs_default.c >> head/sys/kern/vfs_syscalls.c >> head/sys/kern/vfs_vnops.c >> head/sys/kern/vnode_if.src >> head/sys/security/audit/audit_arg.c >> head/sys/sys/vnode.h >> > > What avoidable overhead? The tmpfs_stat handler that you added in your next > commit looks pretty much the same as vop_getattr. I'm missing where the > performance improvement comes from. Could you please fill me in? > -Alan > -- Mateusz Guzik <mjguzik gmail.com>
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