Hi Loïc, > see my comments below (refer also to my comments for > pthread_setaffinity_np.3). Thanks very much! Follow-ups below. [...] >> .TH PTHREAD_ATTR_SETAFFINITY_NP 3 2008-11-05 "Linux" "Linux Programmer's >> Manual" > > Title looks weird on a 80x24 terminal. Yes. But, hard to help -- I couldn't think of a reasonable, more abbreviated name for the page title. >> .SH NAME >> pthread_attr_setaffinity_np, pthread_attr_getaffinity_np \- set/get >> CPU affinity of a thread > > You surely mean: "CPU affinity attribute of a thread" Acchh. You caught cut-and-paste-Pete at work. Fixed: == pthread_attr_setaffinity_np, pthread_attr_getaffinity_np \- set/get CPU affinity attribute in thread attributes object == [...] >> .SH RETURN VALUE >> On success, these functions return 0; >> on error, they return a non-zero error number. >> .SH ERRORS >> .TP >> .B EINVAL >> .I attr >> or >> .I cpuset >> is invalid. > > I beg your pardon, but I couldn't find where those checks are performed in > the relevant glibc files... Perhaps I am not looking at the right place? Hmmm. I'm not sure how I came to add that text. I've removed it now. >> .TP >> .BR EINVAL >> .RB ( pthread_attr_setaffinity_np ()) >> .I cpuset >> specified a CPU that was outside the range >> permitted by the kernel data type >> .\" cpumask_t >> used to represent CPU sets. >> .\" The raw sched_getaffinity() system call returns the size (in bytes) >> .\" of the cpumask_t type. >> This range is determined by the kernel configuration option >> .BR CONFIG_NR_CPUS . (While we're here: I changed the text of this EINVAL error to be the same as the revised EINVAL error text in ptherad_setaffinity_np(3).) > <check> > Hmmm. What does happen if CPU set contains no CPU physically on the system > when the thread is created? I guess pthread_create() fails? > </check> I would expect pthread_create() to fail with EINVAL, and testing confirms this. (There is an EINVAL error diagnostic in pthread_create(3): "Invalid settings in attr".) >> .TP >> .B EINVAL >> .RB ( pthread_getaffinity_np ()) > > This should be: pthread_attr_getaffinity_np(). Fixed now. >> A CPU in the affinity mask of the thread attributes object referred to by >> .I attr >> lies outside the range specified by >> .IR cpusetsize . > > For the application programmer, this means that the structure I passed for > storing the CPU set wasn't big enough to store thread's CPU set without > loosing "affinity information". I simply added the words: (i.e., cpuset/cpusetsize is too small) >> .TP >> .B ENOMEM >> .RB ( pthread_attr_setaffinity_np ()) >> Could not allocate memory. > > Correct. However, the glibc looks somewhat suspicious to me: I had expected > the memory allocated by iattr->cpuset to be bounded (by the size of the > underlying kernel structure). > > Or perhaps I am just missing my coffeine :o Not sure if you are suggesting that I need to change anything here? [...] >> .SH SEE ALSO >> .BR sched_setaffinity (2), >> .BR sched_setscheduler (2), > > Why the reference to sched_setscheduler()? I had thought to include it since it gives some background generally about CPU scheduling. Maybe it's not really necessary: I've removed it now. Thanks for these comments Loic. The revised page is below. Cheers, Michael .\" Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk .\" <mtk.manpages@xxxxxxxxx> .\" .\" Permission is granted to make and distribute verbatim copies of this .\" manual provided the copyright notice and this permission notice are .\" preserved on all copies. .\" .\" Permission is granted to copy and distribute modified versions of this .\" manual under the conditions for verbatim copying, provided that the .\" entire resulting derived work is distributed under the terms of a .\" permission notice identical to this one. .\" .\" Since the Linux kernel and libraries are constantly changing, this .\" manual page may be incorrect or out-of-date. The author(s) assume no .\" responsibility for errors or omissions, or for damages resulting from .\" the use of the information contained herein. The author(s) may not .\" have taken the same level of care in the production of this manual, .\" which is licensed free of charge, as they might when working .\" professionally. .\" .\" Formatted or processed versions of this manual, if unaccompanied by .\" the source, must acknowledge the copyright and authors of this work. .\" .TH PTHREAD_ATTR_SETAFFINITY_NP 3 2008-11-14 "Linux" "Linux Programmer's Manual" .SH NAME pthread_attr_setaffinity_np, pthread_attr_getaffinity_np \- set/get CPU affinity attribute in thread attributes object .SH SYNOPSIS .nf .B #define _GNU_SOURCE .B #include <pthread.h> .BI "int pthread_attr_setaffinity_np(pthread_attr_t " attr , .BI " size_t " cpusetsize ", const cpu_set_t *" cpuset ); .BI "int pthread_attr_getaffinity_np(pthread_attr_t " attr , .BI " size_t " cpusetsize ", cpu_set_t *" cpuset ); .sp Compile and link with \fI\-pthread\fP. .SH DESCRIPTION The .BR pthread_attr_setaffinity_np () sets the CPU affinity mask attribute of the thread attributes object referred to by .I attr to the value specified in .IR cpuset . This attribute determines the CPU affinity mask of a thread created using the thread attributes object .IR attr . The .BR pthread_attr_getaffinity_np () returns the CPU affinity mask attribute of the thread attributes object referred to by .IR attr in the buffer pointed to by .IR cpuset . The argument .I cpusetsize is the length (in bytes) of the buffer pointed to by .IR cpuset . Typically, this argument would be specified as .IR sizeof(cpu_set_t) . For more details on CPU affinity masks, see .BR sched_setaffinity (2). For a description of a set of macros that can be used to manipulate and inspect CPU sets, see .BR CPU_SET (3). .SH RETURN VALUE On success, these functions return 0; on error, they return a non-zero error number. .SH ERRORS .TP .BR EINVAL .RB ( pthread_attr_setaffinity_np ()) .I cpuset specified a CPU that was outside the set supported by the kernel. (The kernel configuration option .BR CONFIG_NR_CPUS defines the range of the set supported by the kernel data type .\" cpumask_t used to represent CPU sets.) .\" The raw sched_getaffinity() system call returns the size (in bytes) .\" of the cpumask_t type. .TP .B EINVAL .RB ( pthread_attr_getaffinity_np ()) A CPU in the affinity mask of the thread attributes object referred to by .I attr lies outside the range specified by .IR cpusetsize (i.e., .IR cpuset / cpusetsize is too small). .TP .B ENOMEM .RB ( pthread_attr_setaffinity_np ()) Could not allocate memory. .SH VERSIONS These functions are provided by glibc since version 2.3.4. .SH CONFORMING TO These functions are non-standard GNU extensions; hence the suffix "_np" (non-portable) in the names. .SH NOTES In glibc 2.3.3 only, versions of these functions were provided that did not have a .I cpusetsize argument. Instead the CPU set size given to the underlying system calls was always .IR sizeof(cpu_set_t) . .SH SEE ALSO .BR sched_setaffinity (2), .BR pthread_attr_init (3), .BR pthread_setaffinity_np (3), .BR cpuset (7), .BR pthreads (7) -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
