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OPNsense - FreeBSD source
bc97daa07e
Reviewed by: Bayard Bell <buffer.g.overflow@gmail.com> Reviewed by: Alek Pinchuk <alek@nexenta.com> Reviewed by: Simon Klinkert <simon.klinkert@gmail.com> Reviewed by: Dan McDonald <danmcd@omniti.com> Approved by: Richard Lowe <richlowe@richlowe.net> Author: Matthew Ahrens <mahrens@delphix.com> illumos/illumos-gate@46e1baa6cf https://www.illumos.org/issues/5911 Sometimes ZFS appears to hang while deleting a file. It is actually making slow progress at the file deletion, but other operations (administrative and writes via the data path) "hang" until the file removal completes, which can take a long time if the file has many blocks. The deletion (or most of it) happens in a single txg, and the sync thread spends most of its time reading indirect blocks via this stack trace: swtch+0x141() cv_wait+0x70() zio_wait+0x5b() dbuf_read+0x2c0() free_children+0x50() free_children+0x12a() free_children+0x12a() free_children+0x12a() dnode_sync_free_range_impl+0xdf() dnode_sync_free_range+0x52() range_tree_vacate+0x65() dnode_sync+0x1d8() dmu_objset_sync_dnodes+0x77() dmu_objset_sync+0x19f() dsl_dataset_sync+0x51() dsl_pool_sync+0x9a() spa_sync+0x2ff() txg_sync_thread+0x21f() thread_start+8() One way to reproduce the problem is if we are over the arc_meta_limit, e.g. because lots of indirect blocks are pinned because we have L0 dbufs under them. It could be that most of the L1 indirects are cached, in which case when dmu_free_long_range_impl() calls dmu_tx_hold_free(), it will complete very quickly. This allows dmu_free_long_range_impl() to put many (perhaps all of its) transactions in the same TXG. However, dmu_free_long_range_impl() calls dnode_evict_dbufs (and dnode_free_range()), which removes the L0 dbufs, thus reducing the hold count on the L1 indirect blocks above it, allowing them to be evicted. Because we are over the arc_meta_limit(), these L1 blocks will be evicted ASAP. Thus when we get to syncing context, the L1 indirects are no longer cached and must be read in. Obtained from: illumos MFC after: 15 days |
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| cddl | ||
| contrib | ||
| crypto | ||
| etc | ||
| games | ||
| gnu | ||
| include | ||
| kerberos5 | ||
| lib | ||
| libexec | ||
| release | ||
| rescue | ||
| sbin | ||
| secure | ||
| share | ||
| sys | ||
| targets | ||
| tests | ||
| tools | ||
| usr.bin | ||
| usr.sbin | ||
| .arcconfig | ||
| .arclint | ||
| COPYRIGHT | ||
| LOCKS | ||
| MAINTAINERS | ||
| Makefile | ||
| Makefile.inc1 | ||
| ObsoleteFiles.inc | ||
| README | ||
| UPDATING | ||
This is the top level of the FreeBSD source directory. This file was last revised on: $FreeBSD$ For copyright information, please see the file COPYRIGHT in this directory (additional copyright information also exists for some sources in this tree - please see the specific source directories for more information). The Makefile in this directory supports a number of targets for building components (or all) of the FreeBSD source tree. See build(7) and http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/makeworld.html for more information, including setting make(1) variables. The `buildkernel` and `installkernel` targets build and install the kernel and the modules (see below). Please see the top of the Makefile in this directory for more information on the standard build targets and compile-time flags. Building a kernel is a somewhat more involved process. See build(7), config(8), and http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/kernelconfig.html for more information. Note: If you want to build and install the kernel with the `buildkernel` and `installkernel` targets, you might need to build world before. More information is available in the handbook. The kernel configuration files reside in the sys/<arch>/conf sub-directory. GENERIC is the default configuration used in release builds. NOTES contains entries and documentation for all possible devices, not just those commonly used. Source Roadmap: --------------- bin System/user commands. cddl Various commands and libraries under the Common Development and Distribution License. contrib Packages contributed by 3rd parties. crypto Cryptography stuff (see crypto/README). etc Template files for /etc. games Amusements. gnu Various commands and libraries under the GNU Public License. Please see gnu/COPYING* for more information. include System include files. kerberos5 Kerberos5 (Heimdal) package. lib System libraries. libexec System daemons. release Release building Makefile & associated tools. rescue Build system for statically linked /rescue utilities. sbin System commands. secure Cryptographic libraries and commands. share Shared resources. sys Kernel sources. tests Regression tests which can be run by Kyua. See tests/README for additional information. tools Utilities for regression testing and miscellaneous tasks. usr.bin User commands. usr.sbin System administration commands. For information on synchronizing your source tree with one or more of the FreeBSD Project's development branches, please see: http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/synching.html