From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753375Ab3JYKuK (ORCPT ); Fri, 25 Oct 2013 06:50:10 -0400 Received: from cantor2.suse.de ([195.135.220.15]:44183 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751459Ab3JYKuJ (ORCPT ); Fri, 25 Oct 2013 06:50:09 -0400 Date: Fri, 25 Oct 2013 21:49:52 +1100 From: NeilBrown To: "Artem S. Tashkinov" Cc: linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, linux-fsdevel@vger.kernel.org, axboe@kernel.dk, linux-mm@kvack.org Subject: Re: Disabling in-memory write cache for x86-64 in Linux II Message-ID: <20131025214952.3eb41201@notabene.brown> In-Reply-To: <160824051.3072.1382685914055.JavaMail.mail@webmail07> References: <160824051.3072.1382685914055.JavaMail.mail@webmail07> X-Mailer: Claws Mail 3.9.0 (GTK+ 2.24.18; x86_64-suse-linux-gnu) Mime-Version: 1.0 Content-Type: multipart/signed; micalg=PGP-SHA1; boundary="Sig_/o0p+.MsNjNOi=r6AgUlpcoW"; protocol="application/pgp-signature" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --Sig_/o0p+.MsNjNOi=r6AgUlpcoW Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable On Fri, 25 Oct 2013 07:25:13 +0000 (UTC) "Artem S. Tashkinov" wrote: > Hello! >=20 > On my x86-64 PC (Intel Core i5 2500, 16GB RAM), I have the same 3.11 kern= el > built for the i686 (with PAE) and x86-64 architectures. What's really tro= ubling me > is that the x86-64 kernel has the following problem: >=20 > When I copy large files to any storage device, be it my HDD with ext4 par= titions > or flash drive with FAT32 partitions, the kernel first caches them in mem= ory entirely > then flushes them some time later (quite unpredictably though) or immedia= tely upon > invoking "sync". >=20 > How can I disable this memory cache altogether (or at least minimize cach= ing)? When > running the i686 kernel with the same configuration I don't observe this = effect - files get > written out almost immediately (for instance "sync" takes less than a sec= ond, whereas > on x86-64 it can take a dozen of _minutes_ depending on a file size and s= torage > performance). What exactly is bothering you about this? The amount of memory used or the time until data is flushed? If the later, then /proc/sys/vm/dirty_expire_centisecs is where you want to look. This defaults to 30 seconds (3000 centisecs). You could make it smaller (providing you also shrink dirty_writeback_centisecs in a similar ratio) and the VM will flush out data more quickly. NeilBrown >=20 > I'm _not_ talking about disabling write cache on my storage itself (hdpar= m -W 0 /dev/XXX) > - firstly this command is detrimental to the performance of my PC, second= ly, it won't help > in this instance. >=20 > Swap is totally disabled, usually my memory is entirely free. >=20 > My kernel configuration can be fetched here: https://bugzilla.kernel.org/= show_bug.cgi?id=3D63531 >=20 > Please, advise. >=20 > Best regards, >=20 > Artem=20 > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ --Sig_/o0p+.MsNjNOi=r6AgUlpcoW Content-Type: application/pgp-signature; name=signature.asc Content-Disposition: attachment; filename=signature.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.19 (GNU/Linux) iQIVAwUBUmpM0Dnsnt1WYoG5AQKbaA/+I+mILT1c0lnYbOi8ARniGUqmGmgqdPhV ywBk0r8Tg2G8uk2hL+KGidXAockhIUOMWWazStHfSIS0OCz3PiAH9zJmExP6Qnng mHsUJbBcaqPnFquUaX+8+zs84Kv4D6RP7hAYaZpkuEDlvrbEXUwnHqKpdEk+RRFv 9bJqEVFHTApcLJ+BHN12UNPRsTXX5Ry10I7IKPJg4col6yZQVWXOvtID7ZrcJt88 IQcLgc6qDVQc6lkKOkrM/5v6oDQy3Ls+VN+6sVvkDtB0s2ZfJeETFNS9JzCWA9N/ 8m65S9oCXBIwNyApYdIf/uMMv+RgmmsosqaJ+KiQLkb5AtnsWUtubuD/4gWQZzJK f6CGinr/ZtzhbhGMq+ogBJ2cOzqbeFGkJlDyGIbNZBrckFRcD80+z0JofTUbQHcN b7ti4NvZzRYDBdkfSL90HMwlpSg26PExxzMbJryxHYAs85DV9nv/PxK+7nSCBhPI 15zziEoty35885Sd94//ECZIiyZINvhCBH6MEzKPq2o3qwlae0egAZowYcdUlSge LRAO8NqVQASqNRj9NE+wYAeEyi0ZRX3yK01lWoV7mYyGNz46gMUYtqeC5+q50GLC dsaQ4preEQHlRsqf8xkYsfZUGTiUa3fWYKiPSXKKIuh2nA8W7IuGDmgdHPj+m1PI Y2E8MBJave0= =w1E3 -----END PGP SIGNATURE----- --Sig_/o0p+.MsNjNOi=r6AgUlpcoW--