From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.org/gmane.linux.lib.musl.general/5911 Path: news.gmane.org!not-for-mail From: Jens Gustedt Newsgroups: gmane.linux.lib.musl.general Subject: Re: Multi-threaded performance progress Date: Tue, 26 Aug 2014 21:34:13 +0200 Message-ID: <1409081653.8054.60.camel@eris.loria.fr> References: <20140826034321.GA13999@brightrain.aerifal.cx> <1409036654.4835.14.camel@eris.loria.fr> <1409070919.8054.47.camel@eris.loria.fr> <20140826175304.GD12888@brightrain.aerifal.cx> <1409077839.8054.54.camel@eris.loria.fr> <20140826190507.GE12888@brightrain.aerifal.cx> Reply-To: musl@lists.openwall.com NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/signed; micalg="pgp-sha1"; protocol="application/pgp-signature"; boundary="=-ohxScXzD+LebgBV261z2" X-Trace: ger.gmane.org 1409081671 31802 80.91.229.3 (26 Aug 2014 19:34:31 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Tue, 26 Aug 2014 19:34:31 +0000 (UTC) To: musl@lists.openwall.com Original-X-From: musl-return-5917-gllmg-musl=m.gmane.org@lists.openwall.com Tue Aug 26 21:34:24 2014 Return-path: Envelope-to: gllmg-musl@plane.gmane.org Original-Received: from mother.openwall.net ([195.42.179.200]) by plane.gmane.org with smtp (Exim 4.69) (envelope-from ) id 1XMMVW-00020F-7v for gllmg-musl@plane.gmane.org; Tue, 26 Aug 2014 21:34:18 +0200 Original-Received: (qmail 5361 invoked by uid 550); 26 Aug 2014 19:34:17 -0000 Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: Original-Received: (qmail 5353 invoked from network); 26 Aug 2014 19:34:17 -0000 X-IronPort-AV: E=Sophos;i="5.04,406,1406584800"; d="scan'";a="91571626" In-Reply-To: <20140826190507.GE12888@brightrain.aerifal.cx> Face: 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 u+rU6wJnprxQf/JvP7beffH5fBIwGIZqEutJUlCKSNoFjYbQiihOkFmih0FJgSUGIpGxstE6RwiLQmsyzcXZesO8N1773YOHKPfUv/uxP726ePjsVNVoT9WZjMq02kRpEKay9+UPXjQmAL1991UuDZ+fGQulSVQrpuqg4pWkkupSjVGshtGZJpzQ9DysfQqZIkgzR7 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 q4emnQ3Df3nxj7z7+t2f+pO/Ysv5U0dm525uKYty3wCetPjRdYNcjaaQabq1Oq1MkVOKkc1reGFhiWIuj7C6JGlKyZNsNor3n7eFStLlkcoKz61fvX/79u3T9cWliTBWvrQEHa0QQmIZgdIK27FQmaKVxIRbN+77z5/4sT/+1PjJEycmosWVmXJvP3YpZM3aNYyuWz 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 xWxyQg9l57BATZZDpuCgH5PMrVxM3G3g513WfNDW3liYRGsPN1ua2LHtq0zM6dOPfmqCDx15227/+ILd58EaNa717/00smp3bsvo7fcS3VpGTcAKV2q1QZJ3MVIC88JsFJN2c+xbrDM+aHPlqE+ji0vY7kWvaFhaaXJzs3nYaoNNq/tJ1/tsiwtnpEOtz/+HHNLMXG 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 1LklihlU2u6NBtNZDaohXHIDKadYWRLsZkZFhgNCaLcB2XzECWalAZhR6v9vzx472v+BF/dxSu3FPf9cY3z0TNLgO+YFNfHzozJHFE4CvW1CPGBvtYabQ5YQuON+aI7YCqUTSX2hgTUeop025IstSiv1wiUQu4fkiz2SBTHaSQ9AQOaZqBk6MTdzFGYAnB0FAvWjD9 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 kELLRU3y0d5Cg1aEZBqSxQJdtprXL5546guXm6QtCwmKOTrvC2NoSq8tw8fYSDx9t8tATVSqNOo16lzdech7Ndrz/a4e/9fqr05+57dCTW7edtz/fE2JIySyHlxqKr8+3OFXooykND8ocf1vwuD1WHO1G5AKPUi5EYVGpLeA4OcqhZtVASKtjkLZFpjM6nZjNG0dnN 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 C3d0WolfKhTp6clRyhcg04xtGCHt1Dh/rExRamYWGyxXa7xn1yYuvkAwP7fClg0Zhx+qr/rM7d+Yesc73nHD5OW7Zh478tRzPxACH/iRa245duzkAdsJfMuy8aXm/FUFlpeWWOm2WZidI9WapaUlFIaTlQ4jfR6/vO9D2NE32LTeYnZOUmnA6PAohx9+qnTy1NnrP/ Cj15cu23XZI4/826Px/xqB37z547sPH374oOvnKTsOb+1zuCoImZARM8ZiLlKkXcWOcoFRJ+Do/CwFO4e2DEe+9Ti+ZXA8ny/cU+X4bMKRZxZIVEiqXI6/+NKuUzPHb7z40ovnX3zx+Ctuq38HyuqWG7Tu+A0AAAAASUVORK5CYII= X-Mailer: Evolution 3.4.4-3 Xref: news.gmane.org gmane.linux.lib.musl.general:5911 Archived-At: --=-ohxScXzD+LebgBV261z2 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: quoted-printable Am Dienstag, den 26.08.2014, 15:05 -0400 schrieb Rich Felker: > On Tue, Aug 26, 2014 at 08:30:39PM +0200, Jens Gustedt wrote: > > Or do you mean that I should use an atomic store at the other end? > > Yes. With an atomic store at the other end, I think it could be > correct, but I'd need to review it further to be sure. ok, it shouldn't be difficult to use atomic ops, then. > > > Note that the performance of the code in which you're trying to avoid > > > the lock does not matter in the slightest except when a race happens > > > between a thread acting on cancellation or timeout and a signaler > > > (since that's the only time it runs). I expect this is extremely rare= , > > > so unless we determine otherwise, I'd rather not add complexity here. > >=20 > > If we have a broadcaster working a long list of waiters, this might > > still happen sufficiently often. And the "complexity" is hidden in the > > execution pattern of the current version, where control and handling > > of the list alternates between different threads, potentially as many > > times as there are waiters in the list. >=20 > Does your code eliminate that all the time? If so it's more > interesting. I'll look at it more. Yes, it will be the signaling or broadcasting thread that will be working on the integrity of the list while it is holding the lock. At the end those that it detected to be leaving will be isolated list items, those that are to be signaled form one consecutive list that is detached from the cv, and the ones that remain (in the signaling case) form a valid cv-with-list. The only small gap that remains (and that annoys me) is the leaving thread that sneaks in - marks itself as leaving before the end of the the CS - only asks for _c_lock *after* the signaling thread has left its CS This is all our problem of late access to the cv variable revisited, but here it is condensed in a very narrow time frame. Both threads must be active for this to happen, so my hope is that when both are spinning for some time on the c_lock for the waiter and on ref for the signaler, none of them will "ever" be forced into a futex wait. Jens --=20 :: INRIA Nancy Grand Est ::: AlGorille ::: ICube/ICPS ::: :: ::::::::::::::: office Strasbourg : +33 368854536 :: :: :::::::::::::::::::::: gsm France : +33 651400183 :: :: ::::::::::::::: gsm international : +49 15737185122 :: :: http://icube-icps.unistra.fr/index.php/Jens_Gustedt :: --=-ohxScXzD+LebgBV261z2 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iEYEABECAAYFAlP84TUACgkQD9PoadrVN+Iu0ACghyy1aAg+5COGC37Bail6VWF3 hHsAnR95rnnpZtk+4lrawFtlfxsvIY5l =V+IE -----END PGP SIGNATURE----- --=-ohxScXzD+LebgBV261z2--