Date: Tue, 18 Nov 2014 14:57:53 -0800 From: Xin Li <delphij@delphij.net> To: Slawa Olhovchenkov <slw@zxy.spb.ru>, Xin LI <delphij@FreeBSD.org> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r274673 - head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs Message-ID: <546BCEF1.7080009@delphij.net> In-Reply-To: <20141118220030.GA31347@zxy.spb.ru> References: <201411181840.sAIIe2C7094558@svn.freebsd.org> <20141118220030.GA31347@zxy.spb.ru>
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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 On 11/18/14 14:00, Slawa Olhovchenkov wrote: > On Tue, Nov 18, 2014 at 06:40:02PM +0000, Xin LI wrote: > >> Author: delphij Date: Tue Nov 18 18:40:01 2014 New Revision: >> 274673 URL: https://svnweb.freebsd.org/changeset/base/274673 >> >> Log: Allow tuning zfs_max_recordsize via loader tunable. Tuning >> is NOT recommended. > > This is not tuning, this is simple guard. And can be safe changed > (incrased, at the least) in any time. FWIW: It can be safely decreased: the ability to read such pool is maintained. > For some workload optimal is maximum, i.e. 16MB. > > May be better comment: increasing this value required strong > understaning after-effects of increasing memory consumption and > bulk data transfers. (sorry for english) That's true, but not free. I don't think we have carefully evaluated the situation (and possible mitigation measures, like, do we need to make some improvements to the slab allocator? It's never exposed to workload like this before, etc.), and people tend to make uninformed changes all the times (a lot of FreeBSD tuning guide gives wrong instructions). >> Requested by: Slawa Olhovchenkov <slw zxy spb ru> MFC after: 2 >> weeks > > Thanks, can you allow RW? Sure, done in 274681. I didn't do it at the beginning because I don't think it's a good idea to make it easy for users to fiddle with it, and power users who actually need to tweak do not change it often. But you are right there is no real technical reason not to allow read-write. >> Modified: >> head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_dataset.c >> >> >> Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_dataset.c >> ============================================================================== >> >> - --- head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_dataset.c Tue Nov 18 18:03:40 2014 (r274672) >> +++ >> head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_dataset.c >> Tue Nov 18 18:40:01 2014 (r274673) @@ -51,6 +51,8 @@ #include >> <sys/dsl_userhold.h> #include <sys/dsl_bookmark.h> >> >> +SYSCTL_DECL(_vfs_zfs); + /* * The SPA supports block sizes up to >> 16MB. However, very large blocks * can have an impact on i/o >> latency (e.g. tying up a spinning disk for @@ -61,6 +63,9 @@ * of >> this setting. */ int zfs_max_recordsize = 1 * 1024 * 1024; >> +SYSCTL_INT(_vfs_zfs, OID_AUTO, max_recordsize, CTLFLAG_RDTUN, + >> &zfs_max_recordsize, 0, + "Maximum block size. Expect dragons >> when tuning this."); >> >> #define SWITCH64(x, y) \ { \ >> _______________________________________________ >> svn-src-all@freebsd.org mailing list >> http://lists.freebsd.org/mailman/listinfo/svn-src-all To >> unsubscribe, send any mail to >> "svn-src-all-unsubscribe@freebsd.org" - -- Xin LI <delphij@delphij.net> https://www.delphij.net/ FreeBSD - The Power to Serve! Live free or die -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0 iQIcBAEBCgAGBQJUa87xAAoJEJW2GBstM+nsPrgP/0o9O/AiiFJZhCezZc29oMQe Za4m5U3sWCPTb1x5fc3A5pKq1frT2GUvbUAjh21yuN5A8GfMt8A4v+nQ4i/asZ3C GkyU7Zkv0sW/14DR3nhRrLTNCum6p2Yk0XkxDBnUlBVzoJzbbbqin9PtTbe6i330 mav6E17V0AelCk8BoWpnhCcQbLObP9zvklzqknjlPHl5d81ERhfyp1p+BjPexdML ykOb3ZsjC0+8MfNmlKEyUga6Saz6vQXVqtXhkMuvqE8VNSfedXO+EpOweOID2SDU 7S4bwkFfu0GuBdqHSXTWsp3ncNiN/KfuX5fAUjb8Aoqp2RCHbft+DS2mnxSw/S7/ cUpOoC1ga+cUU4KLEgm3DG8y1LZH3KPyrzwFzXfY31lgOttCosQi9IeWgigGW975 3jhU7Oz+CX6oMPoAWhujAD3yGKVp2Qp2lePl12pl+F73jrwJ7UaTbKWZlNkofX0T o9/u/tqtna7NY3w9/z7WRDQFZvFEp2laARNAlr8QcakIuCXsDnG26LxFHbtLld0M R/88EYYJgWLPWD7TzapkrKhqbaf6sn6Z7m4M0Oo+MbFRNSII59/rTZsAbDI9PgiZ ScnaQldbnJdi0yMp8VyHrPDFqJtByhL/dQvmcTYf2QItnFEu1Hf3Os1nD+p3+8Z+ sdEBf8XuZdlMIcRIzFR2 =Gccl -----END PGP SIGNATURE-----
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