From owner-svn-src-head@freebsd.org Thu Sep 6 19:42:40 2018 Return-Path: Delivered-To: svn-src-head@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id E115FFE3580; Thu, 6 Sep 2018 19:42:40 +0000 (UTC) (envelope-from mjg@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "mxrelay.nyi.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 96C4088F2F; Thu, 6 Sep 2018 19:42:40 +0000 (UTC) (envelope-from mjg@FreeBSD.org) Received: from repo.freebsd.org (repo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 9181D11A44; Thu, 6 Sep 2018 19:42:40 +0000 (UTC) (envelope-from mjg@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id w86Jgeix078623; Thu, 6 Sep 2018 19:42:40 GMT (envelope-from mjg@FreeBSD.org) Received: (from mjg@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id w86JgeCr078622; Thu, 6 Sep 2018 19:42:40 GMT (envelope-from mjg@FreeBSD.org) Message-Id: <201809061942.w86JgeCr078622@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: mjg set sender to mjg@FreeBSD.org using -f From: Mateusz Guzik Date: Thu, 6 Sep 2018 19:42:40 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r338508 - head/sys/amd64/amd64 X-SVN-Group: head X-SVN-Commit-Author: mjg X-SVN-Commit-Paths: head/sys/amd64/amd64 X-SVN-Commit-Revision: 338508 X-SVN-Commit-Repository: base MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.27 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 06 Sep 2018 19:42:41 -0000 Author: mjg Date: Thu Sep 6 19:42:40 2018 New Revision: 338508 URL: https://svnweb.freebsd.org/changeset/base/338508 Log: amd64: depessimize copyinstr_smap The stac/clac combo around each byte copy is causing a measurable slowdown in benchmarks. Do it only before and after all data is copied. While here reorder the code to avoid a forward branch in the common case. Note the copying loop (originating from copyinstr) is avoidably slow and will be fixed later. Reviewed by: kib Approved by: re (gjb) Differential Revision: https://reviews.freebsd.org/D17063 Modified: head/sys/amd64/amd64/support.S Modified: head/sys/amd64/amd64/support.S ============================================================================== --- head/sys/amd64/amd64/support.S Thu Sep 6 19:28:52 2018 (r338507) +++ head/sys/amd64/amd64/support.S Thu Sep 6 19:42:40 2018 (r338508) @@ -914,6 +914,8 @@ ENTRY(copyinstr_smap) subq %rsi,%rax jbe cpystrflt + stac + /* restrict maxlen to <= VM_MAXUSER_ADDRESS-from */ cmpq %rdx,%rax jae 1f @@ -924,32 +926,20 @@ ENTRY(copyinstr_smap) 2: decq %rdx - jz copyinstr_toolong + jz copyinstr_toolong_smap - stac lodsb stosb - clac orb %al,%al jnz 2b + clac + copyinstr_succ: /* Success -- 0 byte reached */ decq %rdx xorl %eax,%eax - jmp cpystrflt_x -copyinstr_toolong: - /* rdx is zero - return ENAMETOOLONG or EFAULT */ - movq $VM_MAXUSER_ADDRESS,%rax - cmpq %rax,%rsi - jae cpystrflt - movq $ENAMETOOLONG,%rax - jmp cpystrflt_x - /* Fault entry clears PSL.AC */ -cpystrflt: - movq $EFAULT,%rax - cpystrflt_x: /* set *lencopied and return %eax */ movq PCPU(CURPCB),%rcx @@ -962,6 +952,21 @@ cpystrflt_x: 1: POP_FRAME_POINTER ret + /* Fault entry clears PSL.AC */ +cpystrflt: + movq $EFAULT,%rax + jmp cpystrflt_x + +copyinstr_toolong_smap: + clac +copyinstr_toolong: + /* rdx is zero - return ENAMETOOLONG or EFAULT */ + movq $VM_MAXUSER_ADDRESS,%rax + cmpq %rax,%rsi + jae cpystrflt + movq $ENAMETOOLONG,%rax + jmp cpystrflt_x + END(copyinstr_smap) /*