6e2a59181e
When the eviction thread goes to shrink an ARC state, it allocates a set of marker buffers used to hold its place in the state's sublists. This can be problematic in low memory conditions, since 1) the allocation can be substantial, as we allocate NCPU markers; 2) on at least FreeBSD, page reclamation can block in arc_wait_for_eviction() In particular, in stress tests it's possible to hit a deadlock on FreeBSD when the number of free pages is very low, wherein the system is waiting for the page daemon to reclaim memory, the page daemon is waiting for the ARC eviction thread to finish, and the ARC eviction thread is blocked waiting for more memory. Try to reduce the likelihood of such deadlocks by pre-allocating markers for the eviction thread at ARC initialization time. When evicting buffers from an ARC state, check to see if the current thread is the ARC eviction thread, and use the pre-allocated markers for that purpose rather than dynamically allocating them. Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Alexander Motin <mav@FreeBSD.org> Reviewed-by: George Amanakis <gamanakis@gmail.com> Signed-off-by: Mark Johnston <markj@FreeBSD.org> Closes #12985
45 lines
1.3 KiB
C
45 lines
1.3 KiB
C
/*
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* CDDL HEADER START
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*
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* This file and its contents are supplied under the terms of the
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* Common Development and Distribution License ("CDDL"), version 1.0.
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* You may only use this file in accordance with the terms of version
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* 1.0 of the CDDL.
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*
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* A full copy of the text of the CDDL should have accompanied this
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* source. A copy of the CDDL is also available via the Internet at
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* http://www.illumos.org/license/CDDL.
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*
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* CDDL HEADER END
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*/
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/*
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* Copyright (c) 2017, 2018 by Delphix. All rights reserved.
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*/
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#ifndef _SYS_ZTHR_H
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#define _SYS_ZTHR_H
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typedef struct zthr zthr_t;
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typedef void (zthr_func_t)(void *, zthr_t *);
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typedef boolean_t (zthr_checkfunc_t)(void *, zthr_t *);
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extern zthr_t *zthr_create(const char *zthr_name,
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zthr_checkfunc_t checkfunc, zthr_func_t *func, void *arg,
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pri_t pri);
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extern zthr_t *zthr_create_timer(const char *zthr_name,
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zthr_checkfunc_t *checkfunc, zthr_func_t *func, void *arg,
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hrtime_t nano_wait, pri_t pri);
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extern void zthr_destroy(zthr_t *t);
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extern void zthr_wakeup(zthr_t *t);
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extern void zthr_cancel(zthr_t *t);
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extern void zthr_resume(zthr_t *t);
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extern void zthr_wait_cycle_done(zthr_t *t);
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extern boolean_t zthr_iscancelled(zthr_t *t);
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extern boolean_t zthr_iscurthread(zthr_t *t);
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extern boolean_t zthr_has_waiters(zthr_t *t);
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#endif /* _SYS_ZTHR_H */
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