177 lines
3.8 KiB
Groff
177 lines
3.8 KiB
Groff
'\" te
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.\"
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.\" Copyright 2013 Turbo Fredriksson <turbo@bayour.com>. All rights reserved.
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.\"
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.TH SPL-MODULE-PARAMETERS 5 "Nov 18, 2013"
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.SH NAME
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spl\-module\-parameters \- SPL module parameters
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.SH DESCRIPTION
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.sp
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.LP
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Description of the different parameters to the SPL module.
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.SS "Module parameters"
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.sp
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.LP
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.sp
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.ne 2
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.na
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\fBspl_debug_subsys\fR (ulong)
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.ad
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.RS 12n
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Subsystem debugging level mask.
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.sp
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Default value: \fB~0\fR.
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.RE
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.sp
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.ne 2
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.na
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\fBspl_debug_mask\fR (ulong)
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.ad
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.RS 12n
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Debugging level mask.
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.sp
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Default value: \fB8 | 10 | 4 | 20\fR (SD_ERROR | SD_EMERG | SD_WARNING | SD_CONSOLE).
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.RE
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.sp
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.ne 2
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.na
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\fBspl_debug_printk\fR (ulong)
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.ad
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.RS 12n
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Console printk level mask.
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.sp
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Default value: \fB8 | 10 | 4 | 20\fR (SD_ERROR | SD_EMERG | SD_WARNING | SD_CONSOLE).
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.RE
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.sp
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.ne 2
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.na
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\fBspl_debug_mb\fR (int)
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.ad
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.RS 12n
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Total debug buffer size.
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.sp
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Default value: \fB-1\fR.
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.RE
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.sp
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.ne 2
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.na
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\fBspl_debug_panic_on_bug\fR (int)
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.ad
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.RS 12n
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Panic on BUG
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.sp
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Use \fB1\fR for yes and \fB0\fR for no (default).
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.RE
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.sp
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.ne 2
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.na
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\fBspl_kmem_cache_expire\fR (uint)
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.ad
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.RS 12n
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By age (0x1) or low memory (0x2)
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.sp
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Default value: \fB0\fR.
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.RE
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.sp
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.ne 2
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.na
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\fBspl_kmem_alloc_warn\fR (uint)
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.ad
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.RS 12n
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As a general rule kmem_alloc() allocations should be small, preferably
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just a few pages since they must by physically contiguous. Therefore, a
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rate limited warning will be printed to the console for any kmem_alloc()
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which exceeds a reasonable threshold.
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The default warning threshold is set to eight pages but capped at 32K to
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accommodate systems using large pages. This value was selected to be small
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enough to ensure the largest allocations are quickly noticed and fixed.
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But large enough to avoid logging any warnings when a allocation size is
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larger than optimal but not a serious concern. Since this value is tunable,
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developers are encouraged to set it lower when testing so any new largish
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allocations are quickly caught. These warnings may be disabled by setting
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the threshold to zero.
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.sp
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Default value: \fB32K\fR.
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.RE
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.sp
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.ne 2
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.na
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\fBspl_kmem_alloc_max\fR (uint)
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.ad
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.RS 12n
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Large kmem_alloc() allocations will fail if they exceed KMALLOC_MAX_SIZE.
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Allocations which are marginally smaller than this limit may succeed but
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should still be avoided due to the expense of locating a contiguous range
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of free pages. Therefore, a maximum kmem size with reasonable safely
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margin of 4x is set. Kmem_alloc() allocations larger than this maximum
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will quickly fail. Vmem_alloc() allocations less than or equal to this
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value will use kmalloc(), but shift to vmalloc() when exceeding this value.
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.sp
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Default value: \fBKMALLOC_MAX_SIZE/4\fR.
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.RE
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.sp
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.ne 2
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.na
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\fBspl_kmem_cache_magazine_size\fR (uint)
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.ad
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.RS 12n
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Cache magazines are an optimization designed to minimize the cost of
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allocating memory. They do this by keeping a per-cpu cache of recently
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freed objects, which can then be reallocated without taking a lock. This
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can improve performance on highly contended caches. However, because
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objects in magazines will prevent otherwise empty slabs from being
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immediately released this may not be ideal for low memory machines.
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.sp
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For this reason \fBspl_kmem_cache_magazine_size\fR can be used to set a
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maximum magazine size. When this value is set to 0 the magazine size will
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be automatically determined based on the object size. Otherwise magazines
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will be limited to 2-256 objects per magazine (i.e per cpu). Magazines
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may never be entirely disabled in this implementation.
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.sp
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Default value: \fB0\fR.
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.RE
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.sp
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.ne 2
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.na
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\fBspl_hostid\fR (ulong)
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.ad
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.RS 12n
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The system hostid.
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.sp
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Default value: \fB0xFFFFFFFF\fR (an invalid hostid!)
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.RE
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.sp
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.ne 2
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.na
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\fBspl_hostid_path\fR (charp)
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.ad
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.RS 12n
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The system hostid file
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.sp
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Default value: \fB/etc/hostid\fR.
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.RE
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.sp
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.ne 2
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.na
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\fBspl_taskq_thread_bind\fR (int)
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.ad
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.RS 12n
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Bind taskq thread to CPU
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.sp
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Default value: \fB0\fR.
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.RE
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