From owner-svn-src-all@freebsd.org Tue May 28 00:51:24 2019 Return-Path: Delivered-To: svn-src-all@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 9282615AFDDB; Tue, 28 May 2019 00:51:24 +0000 (UTC) (envelope-from dougm@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) server-signature RSA-PSS (4096 bits) client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 328978DFBD; Tue, 28 May 2019 00:51:24 +0000 (UTC) (envelope-from dougm@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 09F2CACAD; Tue, 28 May 2019 00:51:24 +0000 (UTC) (envelope-from dougm@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id x4S0pNVf037777; Tue, 28 May 2019 00:51:23 GMT (envelope-from dougm@FreeBSD.org) Received: (from dougm@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id x4S0pNAe037776; Tue, 28 May 2019 00:51:23 GMT (envelope-from dougm@FreeBSD.org) Message-Id: <201905280051.x4S0pNAe037776@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: dougm set sender to dougm@FreeBSD.org using -f From: Doug Moore Date: Tue, 28 May 2019 00:51:23 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r348318 - head/sys/vm X-SVN-Group: head X-SVN-Commit-Author: dougm X-SVN-Commit-Paths: head/sys/vm X-SVN-Commit-Revision: 348318 X-SVN-Commit-Repository: base MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 328978DFBD X-Spamd-Bar: -- Authentication-Results: mx1.freebsd.org X-Spamd-Result: default: False [-2.96 / 15.00]; local_wl_from(0.00)[FreeBSD.org]; NEURAL_HAM_MEDIUM(-1.00)[-0.999,0]; NEURAL_HAM_SHORT(-0.96)[-0.963,0]; ASN(0.00)[asn:11403, ipnet:2610:1c1:1::/48, country:US]; NEURAL_HAM_LONG(-1.00)[-1.000,0] X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 28 May 2019 00:51:24 -0000 Author: dougm Date: Tue May 28 00:51:23 2019 New Revision: 348318 URL: https://svnweb.freebsd.org/changeset/base/348318 Log: Reduce the code size and number of ffsl calls in vm_reserv_break. Use xor to find where free ranges begin and end. Tested by: pho Reviewed by:alc Approved by:markj, kib (mentors) Differential Revision: https://reviews.freebsd.org/D20256 Modified: head/sys/vm/vm_reserv.c Modified: head/sys/vm/vm_reserv.c ============================================================================== --- head/sys/vm/vm_reserv.c Tue May 28 00:03:46 2019 (r348317) +++ head/sys/vm/vm_reserv.c Tue May 28 00:51:23 2019 (r348318) @@ -1030,56 +1030,49 @@ vm_reserv_alloc_page(int req, vm_object_t object, vm_p static void vm_reserv_break(vm_reserv_t rv) { - int begin_zeroes, hi, i, lo; + u_long changes; + int bitpos, hi, i, lo; vm_reserv_assert_locked(rv); CTR5(KTR_VM, "%s: rv %p object %p popcnt %d inpartpop %d", __FUNCTION__, rv, rv->object, rv->popcnt, rv->inpartpopq); vm_reserv_remove(rv); rv->pages->psind = 0; - i = hi = 0; - do { - /* Find the next 0 bit. Any previous 0 bits are < "hi". */ - lo = ffsl(~(((1UL << hi) - 1) | rv->popmap[i])); - if (lo == 0) { - /* Redundantly clears bits < "hi". */ + hi = lo = -1; + for (i = 0; i <= NPOPMAP; i++) { + /* + * "changes" is a bitmask that marks where a new sequence of + * 0s or 1s begins in popmap[i], with last bit in popmap[i-1] + * considered to be 1 if and only if lo == hi. The bits of + * popmap[-1] and popmap[NPOPMAP] are considered all 1s. + */ + if (i == NPOPMAP) + changes = lo != hi; + else { + changes = rv->popmap[i]; + changes ^= (changes << 1) | (lo == hi); rv->popmap[i] = 0; - rv->popcnt -= NBPOPMAP - hi; - while (++i < NPOPMAP) { - lo = ffsl(~rv->popmap[i]); - if (lo == 0) { - rv->popmap[i] = 0; - rv->popcnt -= NBPOPMAP; - } else - break; + } + while (changes != 0) { + /* + * If the next change marked begins a run of 0s, set + * lo to mark that position. Otherwise set hi and + * free pages from lo up to hi. + */ + bitpos = ffsl(changes) - 1; + changes ^= 1UL << bitpos; + if (lo == hi) + lo = NBPOPMAP * i + bitpos; + else { + hi = NBPOPMAP * i + bitpos; + vm_domain_free_lock(VM_DOMAIN(rv->domain)); + vm_phys_free_contig(&rv->pages[lo], hi - lo); + vm_domain_free_unlock(VM_DOMAIN(rv->domain)); + lo = hi; } - if (i == NPOPMAP) - break; - hi = 0; } - KASSERT(lo > 0, ("vm_reserv_break: lo is %d", lo)); - /* Convert from ffsl() to ordinary bit numbering. */ - lo--; - if (lo > 0) { - /* Redundantly clears bits < "hi". */ - rv->popmap[i] &= ~((1UL << lo) - 1); - rv->popcnt -= lo - hi; - } - begin_zeroes = NBPOPMAP * i + lo; - /* Find the next 1 bit. */ - do - hi = ffsl(rv->popmap[i]); - while (hi == 0 && ++i < NPOPMAP); - if (i != NPOPMAP) - /* Convert from ffsl() to ordinary bit numbering. */ - hi--; - vm_domain_free_lock(VM_DOMAIN(rv->domain)); - vm_phys_free_contig(&rv->pages[begin_zeroes], NBPOPMAP * i + - hi - begin_zeroes); - vm_domain_free_unlock(VM_DOMAIN(rv->domain)); - } while (i < NPOPMAP); - KASSERT(rv->popcnt == 0, - ("vm_reserv_break: reserv %p's popcnt is corrupted", rv)); + } + rv->popcnt = 0; counter_u64_add(vm_reserv_broken, 1); }