Date: Tue, 29 Jan 2019 19:34:32 -0500 From: Mark Johnston <markj@freebsd.org> To: Marko Zec <zec@fer.hr> Cc: src-committers@freebsd.org, svn-src-all@freebsd.org Subject: Re: svn commit: r343527 - in stable/12/sys/riscv: include riscv Message-ID: <20190130003432.GA2617@spy> In-Reply-To: <20190129192627.51acc721@x23> References: <201901281614.x0SGErMq078921@repo.freebsd.org> <20190129192627.51acc721@x23>
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On Tue, Jan 29, 2019 at 07:26:27PM +0100, Marko Zec wrote: > On Mon, 28 Jan 2019 16:14:53 +0000 > Mark Johnston <markj@freebsd.org> wrote: > > > Author: markj > > Date: Mon Jan 28 16:14:53 2019 > > New Revision: 343527 > > URL: https://svnweb.freebsd.org/changeset/base/343527 > > > > Log: > > MFC r343274, r343275: > > Optimize RISC-V copyin(9)/copyout(9) routines. > > Was this subjected to any benchmarks? I'd bet that placing I only did some ad-hoc testing under QEMU with a few copyout()-intensive programs (a few procstat(1) invocations). In general I saw a roughly 5% decrease in runtimes. I don't yet have any hardware to test on, and I don't believe Mitchell (the submitter of the patch) does either. > addi a2, a2, -XLEN_BYTES > > before > > sd a4, 0(a1) > > instead of being scheduled after (the same goes for the byte copy loop) > would make the loops run faster on most in-order RV cores out there... That makes sense. I doubt it would make a difference under QEMU though.
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