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Manual typos: Resource Usage and Limitation 

2016-05-06  Rical Jasan  <ricaljasan@pacific.net>

	* manual/resource.texi: Fix typos in the manual.
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Rical Jasan 2016-10-06 12:16:53 +05:30 committed by Siddhesh Poyarekar
parent 9269924c82
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@ -1,5 +1,7 @@
2016-10-06 Rical Jasan <ricaljasan@pacific.net> 2016-10-06 Rical Jasan <ricaljasan@pacific.net>
* manual/resource.texi: Fix typos in the manual.
* manual/time.texi: Fix typos in the manual. * manual/time.texi: Fix typos in the manual.
* manual/arith.texi: Fix typos in the manual. * manual/arith.texi: Fix typos in the manual.

52
manual/resource.texi
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@ -452,7 +452,7 @@ above do. The functions above are better choices.
@code{ulimit} gets the current limit or sets the current and maximum @code{ulimit} gets the current limit or sets the current and maximum
limit for a particular resource for the calling process according to the limit for a particular resource for the calling process according to the
command @var{cmd}.a command @var{cmd}.
If you are getting a limit, the command argument is the only argument. If you are getting a limit, the command argument is the only argument.
If you are setting a limit, there is a second argument: If you are setting a limit, there is a second argument:
@ -652,7 +652,7 @@ instructions for your process.
Similarly, a page fault causes what looks like a straightforward Similarly, a page fault causes what looks like a straightforward
sequence of instructions to take a long time. The fact that other sequence of instructions to take a long time. The fact that other
processes get to run while the page faults in is of no consequence, processes get to run while the page faults in is of no consequence,
because as soon as the I/O is complete, the high priority process will because as soon as the I/O is complete, the higher priority process will
kick them out and run again, but the wait for the I/O itself could be a kick them out and run again, but the wait for the I/O itself could be a
problem. To neutralize this threat, use @code{mlock} or problem. To neutralize this threat, use @code{mlock} or
@code{mlockall}. @code{mlockall}.
@ -668,7 +668,7 @@ order to run. The errant program is in complete control. It controls
the vertical, it controls the horizontal. the vertical, it controls the horizontal.
There are two ways to avoid this: 1) keep a shell running somewhere with There are two ways to avoid this: 1) keep a shell running somewhere with
a higher absolute priority. 2) keep a controlling terminal attached to a higher absolute priority or 2) keep a controlling terminal attached to
the high priority process group. All the priority in the world won't the high priority process group. All the priority in the world won't
stop an interrupt handler from running and delivering a signal to the stop an interrupt handler from running and delivering a signal to the
process if you hit Control-C. process if you hit Control-C.
@ -733,7 +733,7 @@ between Round Robin and First Come First Served.
To understand how scheduling works when processes of different scheduling To understand how scheduling works when processes of different scheduling
policies occupy the same absolute priority, you have to know the nitty policies occupy the same absolute priority, you have to know the nitty
gritty details of how processes enter and exit the ready to run list: gritty details of how processes enter and exit the ready to run list.
In both cases, the ready to run list is organized as a true queue, where In both cases, the ready to run list is organized as a true queue, where
a process gets pushed onto the tail when it becomes ready to run and is a process gets pushed onto the tail when it becomes ready to run and is
@ -931,7 +931,7 @@ you want to know.
absolute priority of the process. absolute priority of the process.
On success, the return value is @code{0}. Otherwise, it is @code{-1} On success, the return value is @code{0}. Otherwise, it is @code{-1}
and @code{ERRNO} is set accordingly. The @code{errno} values specific and @code{errno} is set accordingly. The @code{errno} values specific
to this function are: to this function are:
@table @code @table @code
@ -1067,7 +1067,7 @@ among the great unwashed processes gets them.
@subsubsection Introduction To Traditional Scheduling @subsubsection Introduction To Traditional Scheduling
Long before there was absolute priority (See @ref{Absolute Priority}), Long before there was absolute priority (See @ref{Absolute Priority}),
Unix systems were scheduling the CPU using this system. When Posix came Unix systems were scheduling the CPU using this system. When POSIX came
in like the Romans and imposed absolute priorities to accommodate the in like the Romans and imposed absolute priorities to accommodate the
needs of realtime processing, it left the indigenous Absolute Priority needs of realtime processing, it left the indigenous Absolute Priority
Zero processes to govern themselves by their own familiar scheduling Zero processes to govern themselves by their own familiar scheduling
@ -1095,7 +1095,7 @@ The dynamic priority sometimes determines who gets the next turn on the
CPU. Sometimes it determines how long turns last. Sometimes it CPU. Sometimes it determines how long turns last. Sometimes it
determines whether a process can kick another off the CPU. determines whether a process can kick another off the CPU.
In Linux, the value is a combination of these things, but mostly it is In Linux, the value is a combination of these things, but mostly it
just determines the length of the time slice. The higher a process' just determines the length of the time slice. The higher a process'
dynamic priority, the longer a shot it gets on the CPU when it gets one. dynamic priority, the longer a shot it gets on the CPU when it gets one.
If it doesn't use up its time slice before giving up the CPU to do If it doesn't use up its time slice before giving up the CPU to do
@ -1124,7 +1124,7 @@ ability to refuse its equal share of CPU time that others might prosper.
Hence, the higher a process' nice value, the nicer the process is. Hence, the higher a process' nice value, the nicer the process is.
(Then a snake came along and offered some process a negative nice value (Then a snake came along and offered some process a negative nice value
and the system became the crass resource allocation system we know and the system became the crass resource allocation system we know
today). today.)
Dynamic priorities tend upward and downward with an objective of Dynamic priorities tend upward and downward with an objective of
smoothing out allocation of CPU time and giving quick response time to smoothing out allocation of CPU time and giving quick response time to
@ -1181,7 +1181,7 @@ have the same nice value, this returns the lowest value that any of them
has. has.
On success, the return value is @code{0}. Otherwise, it is @code{-1} On success, the return value is @code{0}. Otherwise, it is @code{-1}
and @code{ERRNO} is set accordingly. The @code{errno} values specific and @code{errno} is set accordingly. The @code{errno} values specific
to this function are: to this function are:
@table @code @table @code
@ -1306,7 +1306,7 @@ over this aspect of the system as well:
@item @item
One thread or process is responsible for absolutely critical work One thread or process is responsible for absolutely critical work
which under no circumstances must be interrupted or hindered from which under no circumstances must be interrupted or hindered from
making process by other process or threads using CPU resources. In making progress by other processes or threads using CPU resources. In
this case the special process would be confined to a CPU which no this case the special process would be confined to a CPU which no
other process or thread is allowed to use. other process or thread is allowed to use.
@ -1316,7 +1316,7 @@ from different CPUs. This is the case in NUMA (Non-Uniform Memory
Architecture) machines. Preferably memory should be accessed locally Architecture) machines. Preferably memory should be accessed locally
but this requirement is usually not visible to the scheduler. but this requirement is usually not visible to the scheduler.
Therefore forcing a process or thread to the CPUs which have local Therefore forcing a process or thread to the CPUs which have local
access to the mostly used memory helps to significantly boost the access to the most-used memory helps to significantly boost the
performance. performance.
@item @item
@ -1331,7 +1331,7 @@ problem. The Linux kernel provides a set of interfaces to allow
specifying @emph{affinity sets} for a process. The scheduler will specifying @emph{affinity sets} for a process. The scheduler will
schedule the thread or process on CPUs specified by the affinity schedule the thread or process on CPUs specified by the affinity
masks. The interfaces which @theglibc{} define follow to some masks. The interfaces which @theglibc{} define follow to some
extend the Linux kernel interface. extent the Linux kernel interface.
@comment sched.h @comment sched.h
@comment GNU @comment GNU
@ -1345,7 +1345,7 @@ different interface has to be used.
This type is a GNU extension and is defined in @file{sched.h}. This type is a GNU extension and is defined in @file{sched.h}.
@end deftp @end deftp
To manipulate the bitset, to set and reset bits, a number of macros is To manipulate the bitset, to set and reset bits, a number of macros are
defined. Some of the macros take a CPU number as a parameter. Here defined. Some of the macros take a CPU number as a parameter. Here
it is important to never exceed the size of the bitset. The following it is important to never exceed the size of the bitset. The following
macro specifies the number of bits in the @code{cpu_set_t} bitset. macro specifies the number of bits in the @code{cpu_set_t} bitset.
@ -1432,7 +1432,7 @@ affinity mask can be retrieved from the system.
@c Wrapped syscall to zero out past the kernel cpu set size; Linux @c Wrapped syscall to zero out past the kernel cpu set size; Linux
@c only. @c only.
This functions stores the CPU affinity mask for the process or thread This function stores the CPU affinity mask for the process or thread
with the ID @var{pid} in the @var{cpusetsize} bytes long bitmap with the ID @var{pid} in the @var{cpusetsize} bytes long bitmap
pointed to by @var{cpuset}. If successful, the function always pointed to by @var{cpuset}. If successful, the function always
initializes all bits in the @code{cpu_set_t} object and returns zero. initializes all bits in the @code{cpu_set_t} object and returns zero.
@ -1446,7 +1446,7 @@ and @code{errno} is set to represent the error condition.
No process or thread with the given ID found. No process or thread with the given ID found.
@item EFAULT @item EFAULT
The pointer @var{cpuset} is does not point to a valid object. The pointer @var{cpuset} does not point to a valid object.
@end table @end table
This function is a GNU extension and is declared in @file{sched.h}. This function is a GNU extension and is declared in @file{sched.h}.
@ -1465,7 +1465,7 @@ interface must be provided for that.
This function installs the @var{cpusetsize} bytes long affinity mask This function installs the @var{cpusetsize} bytes long affinity mask
pointed to by @var{cpuset} for the process or thread with the ID @var{pid}. pointed to by @var{cpuset} for the process or thread with the ID @var{pid}.
If successful the function returns zero and the scheduler will in future If successful the function returns zero and the scheduler will in the future
take the affinity information into account. take the affinity information into account.
If the function fails it will return @code{-1} and @code{errno} is set If the function fails it will return @code{-1} and @code{errno} is set
@ -1476,7 +1476,7 @@ to the error code:
No process or thread with the given ID found. No process or thread with the given ID found.
@item EFAULT @item EFAULT
The pointer @var{cpuset} is does not point to a valid object. The pointer @var{cpuset} does not point to a valid object.
@item EINVAL @item EINVAL
The bitset is not valid. This might mean that the affinity set might The bitset is not valid. This might mean that the affinity set might
@ -1518,7 +1518,7 @@ virtual addresses into physical addresses. This is normally done by the
hardware of the processor. hardware of the processor.
@cindex shared memory @cindex shared memory
Using a virtual address space has several advantage. The most important Using a virtual address space has several advantages. The most important
is process isolation. The different processes running on the system is process isolation. The different processes running on the system
cannot interfere directly with each other. No process can write into cannot interfere directly with each other. No process can write into
the address space of another process (except when shared memory is used the address space of another process (except when shared memory is used
@ -1548,16 +1548,16 @@ stores memory content externally it cannot do this on a byte-by-byte
basis. The administrative overhead does not allow this (leaving alone basis. The administrative overhead does not allow this (leaving alone
the processor hardware). Instead several thousand bytes are handled the processor hardware). Instead several thousand bytes are handled
together and form a @dfn{page}. The size of each page is always a power together and form a @dfn{page}. The size of each page is always a power
of two byte. The smallest page size in use today is 4096, with 8192, of two bytes. The smallest page size in use today is 4096, with 8192,
16384, and 65536 being other popular sizes. 16384, and 65536 being other popular sizes.
@node Query Memory Parameters @node Query Memory Parameters
@subsection How to get information about the memory subsystem? @subsection How to get information about the memory subsystem?
The page size of the virtual memory the process sees is essential to The page size of the virtual memory the process sees is essential to
know in several situations. Some programming interface (e.g., know in several situations. Some programming interfaces (e.g.,
@code{mmap}, @pxref{Memory-mapped I/O}) require the user to provide @code{mmap}, @pxref{Memory-mapped I/O}) require the user to provide
information adjusted to the page size. In the case of @code{mmap} is it information adjusted to the page size. In the case of @code{mmap} it is
necessary to provide a length argument which is a multiple of the page necessary to provide a length argument which is a multiple of the page
size. Another place where the knowledge about the page size is useful size. Another place where the knowledge about the page size is useful
is in memory allocation. If one allocates pieces of memory in larger is in memory allocation. If one allocates pieces of memory in larger
@ -1568,7 +1568,7 @@ of the page size the kernel's memory handling can work more effectively
since it only has to allocate memory pages which are fully used. (To do since it only has to allocate memory pages which are fully used. (To do
this optimization it is necessary to know a bit about the memory this optimization it is necessary to know a bit about the memory
allocator which will require a bit of memory itself for each block and allocator which will require a bit of memory itself for each block and
this overhead must not push the total size over the page size multiple. this overhead must not push the total size over the page size multiple.)
The page size traditionally was a compile time constant. But recent The page size traditionally was a compile time constant. But recent
development of processors changed this. Processors now support development of processors changed this. Processors now support
@ -1605,7 +1605,7 @@ information about the physical memory the system has. The call
@end smallexample @end smallexample
@noindent @noindent
returns the total number of pages of physical the system has. returns the total number of pages of physical memory the system has.
This does not mean all this memory is available. This information can This does not mean all this memory is available. This information can
be found using be found using
@ -1634,7 +1634,7 @@ get this information two functions. They are declared in the file
@safety{@prelim{}@mtsafe{}@asunsafe{@ascuheap{} @asulock{}}@acunsafe{@aculock{} @acsfd{} @acsmem{}}} @safety{@prelim{}@mtsafe{}@asunsafe{@ascuheap{} @asulock{}}@acunsafe{@aculock{} @acsfd{} @acsmem{}}}
@c This fopens a /proc file and scans it for the requested information. @c This fopens a /proc file and scans it for the requested information.
The @code{get_phys_pages} function returns the total number of pages of The @code{get_phys_pages} function returns the total number of pages of
physical the system has. To get the amount of memory this number has to physical memory the system has. To get the amount of memory this number has to
be multiplied by the page size. be multiplied by the page size.
This function is a GNU extension. This function is a GNU extension.
@ -1645,7 +1645,7 @@ This function is a GNU extension.
@deftypefun {long int} get_avphys_pages (void) @deftypefun {long int} get_avphys_pages (void)
@safety{@prelim{}@mtsafe{}@asunsafe{@ascuheap{} @asulock{}}@acunsafe{@aculock{} @acsfd{} @acsmem{}}} @safety{@prelim{}@mtsafe{}@asunsafe{@ascuheap{} @asulock{}}@acunsafe{@aculock{} @acsfd{} @acsmem{}}}
The @code{get_avphys_pages} function returns the number of available pages of The @code{get_avphys_pages} function returns the number of available pages of
physical the system has. To get the amount of memory this number has to physical memory the system has. To get the amount of memory this number has to
be multiplied by the page size. be multiplied by the page size.
This function is a GNU extension. This function is a GNU extension.
@ -1712,7 +1712,7 @@ This function is a GNU extension.
Before starting more threads it should be checked whether the processors Before starting more threads it should be checked whether the processors
are not already overused. Unix systems calculate something called the are not already overused. Unix systems calculate something called the
@dfn{load average}. This is a number indicating how many processes were @dfn{load average}. This is a number indicating how many processes were
running. This number is average over different periods of times running. This number is an average over different periods of time
(normally 1, 5, and 15 minutes). (normally 1, 5, and 15 minutes).
@comment stdlib.h @comment stdlib.h