pmemblk_ctl_get(3)

1PMEMBLK_CTL_GET(3)         PMDK Programmer's Manual         PMEMBLK_CTL_GET(3)
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NAME

6       pmemblk_ctl_get(),  pmemblk_ctl_set(),  pmemblk_ctl_exec()  - Query and
7       modify libpmemblk internal behavior (EXPERIMENTAL)
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SYNOPSIS

10              #include <libpmemblk.h>
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12              int pmemblk_ctl_get(PMEMblkpool *pbp, const char *name, void *arg); (EXPERIMENTAL)
13              int pmemblk_ctl_set(PMEMblkpool *pbp, const char *name, void *arg); (EXPERIMENTAL)
14              int pmemblk_ctl_exec(PMEMblkpool *pbp, const char *name, void *arg); (EXPERIMENTAL)
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DESCRIPTION

17       The pmemblk_ctl_get(), pmemblk_ctl_set() and  pmemblk_ctl_exec()  func‐
18       tions provide a uniform interface for querying and modifying the inter‐
19       nal behavior of libpmemblk(7) through the control (CTL) namespace.
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21       The name argument specifies an entry point as defined in the CTL names‐
22       pace  specification.  The entry point description specifies whether the
23       extra arg is required.  Those two  parameters  together  create  a  CTL
24       query.  The functions and the entry points are thread-safe unless indi‐
25       cated otherwise below.  If there are special conditions for calling  an
26       entry  point, they are explicitly stated in its description.  The func‐
27       tions propagate the return value of the entry point.  If either name or
28       arg is invalid, -1 is returned.
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30       If  the  provided ctl query is valid, the CTL functions will always re‐
31       turn 0 on success and -1 on failure, unless otherwise specified in  the
32       entry point description.
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34       See more in pmem_ctl(5) man page.
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CTL NAMESPACE

37       prefault.at_create | rw | global | int | int | - | boolean
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39       If  set, every page of the pool will be touched and written to when the
40       pool is created, in order to trigger page allocation and  minimize  the
41       performance  impact  of  pagefaults.  Affects only the pmemblk_create()
42       function.
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44       Always returns 0.
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46       prefault.at_open | rw | global | int | int | - | boolean
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48       If set, every page of the pool will be touched and written to when  the
49       pool  is  opened,  in order to trigger page allocation and minimize the
50       performance impact of  pagefaults.   Affects  only  the  pmemblk_open()
51       function.
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53       Always returns 0.
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55       sds.at_create | rw | global | int | int | - | boolean
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57       If  set,  force-enables  or force-disables SDS feature during pool cre‐
58       ation.  Affects only the pmemblk_create() function.  See  pmempool_fea‐
59       ture_query(3) for information about SDS (SHUTDOWN_STATE) feature.
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61       Always returns 0.
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63       copy_on_write.at_open | rw | global | int | int | - | boolean
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65       If set, pool is mapped in such a way that modifications don't reach the
66       underlying medium.  From the user's perspective this  means  that  when
67       the  pool is closed all changes are reverted.  This feature is not sup‐
68       ported for pools located on Device DAX.
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70       Always returns 0.
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CTL EXTERNAL CONFIGURATION

73       In addition to direct function call, each write entry point can also be
74       set using two alternative methods.
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76       The  first  method  is  to load a configuration directly from the PMEM‐
77       BLK_CONF environment variable.
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79       The second method of loading an external configuration is  to  set  the
80       PMEMBLK_CONF_FILE environment variable to point to a file that contains
81       a sequence of ctl queries.
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83       See more in pmem_ctl(5) man page.
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NAME

SYNOPSIS

DESCRIPTION

CTL NAMESPACE

CTL EXTERNAL CONFIGURATION

SEE ALSO