From mboxrd@z Thu Jan 1 00:00:00 1970 From: Loic Dachary Subject: Improving latency and ordering of the backfilling workload Date: Mon, 15 Dec 2014 15:24:44 +0100 Message-ID: <548EEF2C.1010703@dachary.org> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="3vEAI3Wd3Om1smSD78PJr5GFpMVlUJHCq" Return-path: Received: from mail2.dachary.org ([91.121.57.175]:53221 "EHLO smtp.dmail.dachary.org" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750711AbaLOOYq (ORCPT ); Mon, 15 Dec 2014 09:24:46 -0500 Sender: ceph-devel-owner@vger.kernel.org List-ID: To: Samuel Just Cc: Ceph Development This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --3vEAI3Wd3Om1smSD78PJr5GFpMVlUJHCq Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Hi Sam, Here is what could be done (in the context of http://tracker.ceph.com/iss= ues/9566 ), please let me know if that makes sense: * ordering: * when dequeuing a pending local reservation, chose one that contains a= PG that belongs to the busiest OSD (i.e. the OSD for which there are mor= e PGs waiting for a local reservation than any other) * when sending a remote reservation request, set the priority to reflec= t the total number of pending PG (absolute workload) and the number local= pending PG for the destination OSD (workload queued locally for the remo= te OSD) * on the receiving side, the priority of the remote reservation request= makes sure the busiest OSD gets a remote reservation before the others * reducing latency: =20 * if there are N pending remote reservations, reject a remote reservati= on request instead of queuing it so that the local reservation can be use= d instead of waiting. Cheers --=20 Lo=C3=AFc Dachary, Artisan Logiciel Libre --3vEAI3Wd3Om1smSD78PJr5GFpMVlUJHCq Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.22 (GNU/Linux) iEYEARECAAYFAlSO7ywACgkQ8dLMyEl6F23TdgCgrV1e0mWsOuKyDdHFIJCcdWfY cT0AmQHHpU84HW+aQxhmWIHUxT40Jl9z =NsTa -----END PGP SIGNATURE----- --3vEAI3Wd3Om1smSD78PJr5GFpMVlUJHCq--