Date: Tue, 18 Mar 2014 12:00:23 +0000 From: Matthew Seaman <matthew@freebsd.org> To: freebsd-performance@freebsd.org Subject: Re: FreeBSD 10 and PostgreSQL 9.3 scalability issues Message-ID: <53283557.4070105@freebsd.org> In-Reply-To: <5327B9B7.3050103@gmail.com> References: <5327B9B7.3050103@gmail.com>
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This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --TrvE6DU40kixEQgjbS3vUXBPeNnSpjw8k Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 03/18/14 03:12, Petr Janda wrote: > ust want to share these pgbench results done by DragonFlyBSD, and would= > like some input on why these numbers look so bad and what can be done t= o > improve (ie. kernel tunables etc) the performance. >=20 > http://lists.dragonflybsd.org/pipermail/users/attachments/20140310/4250= b961/attachment-0001.pdf Using ZFS as the backing for a RDBMS without: * Separate (fast) L2ARC devices * Tuning the ZFS block size to match the postgres IO block size * Setting primarycache to metadata * Tuning the ARC max so ZFS doesn't eat all the RAM * probably other things I can remember off-hand. That's what is wrong. ZFS is known to work particularly badly at the sort of small random IOs that RDBMSes generate (mostly because of the copy-on-write thing) without special tuning and extra hardware for caches. ie. You can't construct a fair test of database performance against other OSes/filesystems if you restrict yourself to using exactly the same hardware. Basically, install the FreeBSD box on UFS2 and try again. Cheers, Matthew --TrvE6DU40kixEQgjbS3vUXBPeNnSpjw8k 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 (FreeBSD) Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQJ8BAEBCgBmBQJTKDVgXxSAAAAAAC4AKGlzc3Vlci1mcHJAbm90YXRpb25zLm9w ZW5wZ3AuZmlmdGhob3JzZW1hbi5uZXQxOUYxNTRFQ0JGMTEyRTUwNTQ0RTNGMzAw MDUxM0YxMEUwQTlFNEU3AAoJEABRPxDgqeTnFjYP/RL9xQktUXOHKTQLGSoPrH7b mrprdljjuIa8LHKhh08zyiAwU3V+OIk2JDYX4rSAjLYryRNWMEkEjNi7DTctgJny r5yefOGParhOTP6p9hxaxm2qFUQpPBjSS1V/+Igrd8DEjmfI6Uy5VwJwYR1nfQBQ lLf4Kpa9EUMSZnoJk+4SusoweySjcUBq0BjoGt+1wXpjk4410V38gDEVvdT3APe+ QKkobicvSWkjyrVkZ+o1kskjbvSxFefgc5POYOaJeCKrfgVWvFGirwT7vn8nEZ7N EkALwBtofOIKGeXENUMfH5zCdXVEw/D1zoMEQL0n0SPEuq/1GG9nm+Kvqsf7Z0zp 02PWOGzhbBdHE5Vng/o627wMUd2YrsjFxRkYEiq89sxQTmBqNGDWU+LA+WIi3xGT PUHMPwp/6xEIpLnXf2kxZMwt4fwEPiCJxJSzgKK2lmgj/8eIKjWNWbyyFEIsZMQp Q4LRJ9zFDo5rBe+Mo2du4M2B+vyismUsxr34l7lNXPQ4WiPLY69EbiJA24oBC+zI QsZWEUKHChdlnETeVcCwAA3bMB3Q3UmCHczTGktz0JGfpAQ5j9FpVlxbFkV/P9++ OEi4MFpDNzCJAJY5rS7wr5deROZzcpeFBDvbGsv5nkXhAlzqbUeX8EsJO+4AiPBH 9lYFQGVdJA39ttfg7JK5 =fodm -----END PGP SIGNATURE----- --TrvE6DU40kixEQgjbS3vUXBPeNnSpjw8k--
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