Date: Wed, 8 Jul 2015 11:29:01 -0700 From: hiren panchasara <hiren@FreeBSD.org> To: Alan Cox <alc@FreeBSD.org> Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r285282 - head/sys/vm Message-ID: <20150708182901.GJ51988@strugglingcoder.info> In-Reply-To: <201507081746.t68Hk0To044278@repo.freebsd.org> References: <201507081746.t68Hk0To044278@repo.freebsd.org>
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--451BZW+OUuJBCAYj Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On 07/08/15 at 05:46P, Alan Cox wrote: > Author: alc > Date: Wed Jul 8 17:45:59 2015 > New Revision: 285282 > URL: https://svnweb.freebsd.org/changeset/base/285282 >=20 > Log: > The intention of r254304 was to scan the active queue continuously. > However, I've observed the active queue scan stopping when there are > frequent free page shortages and the inactive queue is steadily refilled > by other mechanisms, such as the sequential access heuristic in vm_faul= t() > or madvise(2).=20 What would be the actual downside/effect of this scenario? i.e. What goes wrong when active queue scan stops and what would I see/observe on a system when the problem is going on - is what I want to understand. > To remedy this problem, record the time of the last active > queue scan, and always scan a number of pages proportional to the time > since the last scan, regardless of whether that last scan was a > timeout-triggered ("pass =3D=3D 0") or free-page-shortage-triggered ("p= ass > > 0") scan. > =20 > Also, on a timeout-triggered scan, allow a full scan of the active queue > when the system is short of inactive pages. > =20 > Reviewed by: kib > MFC after: 6 weeks > Sponsored by: EMC / Isilon Storage Division [skip] Thanks in advance. Cheers, Hiren --451BZW+OUuJBCAYj Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.22 (FreeBSD) iQF8BAEBCgBmBQJVnWvtXxSAAAAAAC4AKGlzc3Vlci1mcHJAbm90YXRpb25zLm9w ZW5wZ3AuZmlmdGhob3JzZW1hbi5uZXRBNEUyMEZBMUQ4Nzg4RjNGMTdFNjZGMDI4 QjkyNTBFMTU2M0VERkU1AAoJEIuSUOFWPt/lNHYH+waL0+YG6SEy6g11jr2F3R2Y s4fxLWMlyY05g3Sdvluy3AWRBu0vMT/shQY//WfzrreaxpYXEfsL4428YYrtQ5m2 S8d50vNB6URdTaYTUleRCrzcg5/bzhb6yKPdI/9WWh7xzlBzUxv/+N3wh5KDRUD7 yiIRKoKCcVucDew0XClp/PDzsNjqQyRpHgDfYLv6fuCJh4e0ljowPgLu/3DC7xDy r/Z+Zf6SDzo6vwWXky3DSCXQuPR72HkX8jo8FDli44FrXFmXYaLKWCorLQSIVwGW pEeAe5XJkKh3M6LMCX5IFPrKIdeIeLBiWueciSCdUrwQFLC0keFGHx59sKzrIJg= =zQoP -----END PGP SIGNATURE----- --451BZW+OUuJBCAYj--
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