[PATCH] proc.5: details for threads-max

[PATCH] proc.5: details for threads-max

[Heinrich Schuchardt]

Add detail information for threads-max.
The checks for minimum and maximum values exist since kernel 4.1.
https://lkml.org/lkml/2015/3/15/96

Signed-off-by: Heinrich Schuchardt <xypron.glpk-Mmb7MZpHnFY@public.gmane.org>
---
 man5/proc.5 | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/man5/proc.5 b/man5/proc.5
index bb648d4..83f30af 100644
--- a/man5/proc.5
+++ b/man5/proc.5
@@ -4265,8 +4265,22 @@ this is the fifth kernel built from this source base and the
 date following it indicates the time the kernel was built.
 .TP
 .IR /proc/sys/kernel/threads-max " (since Linux 2.3.11)"
+.\" The following is based on Documentation/sysctl/kernel.txt
 This file specifies the system-wide limit on the number of
 threads (tasks) that can be created on the system.
+
+The minimum value that can be written to threads-max is 20.
+The maximum value that can be written to threads-max is given by the
+constant
+.B FUTEX_TID_MASK
+(0x3fffffff).
+If a value outside of this range is written to threads-max an error
+.B EINVAL
+occurs.
+
+The value written is checked against the available RAM pages.
+If the thread structures would occupy too much (more than 1/8th)
+of the available RAM pages, threads-max is reduced accordingly.
 .TP
 .IR /proc/sys/kernel/zero-paged " (PowerPC only) "
 This file
-- 
2.1.4

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Re: [PATCH] proc.5: details for threads-max

[Michael Kerrisk (man-pages)]

Hello Heinrich,

On 08/25/2015 11:36 PM, Heinrich Schuchardt wrote:
> Add detail information for threads-max.
> The checks for minimum and maximum values exist since kernel 4.1.
> https://lkml.org/lkml/2015/3/15/96
> 
> Signed-off-by: Heinrich Schuchardt <xypron.glpk-Mmb7MZpHnFY@public.gmane.org>
> ---
>  man5/proc.5 | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/man5/proc.5 b/man5/proc.5
> index bb648d4..83f30af 100644
> --- a/man5/proc.5
> +++ b/man5/proc.5
> @@ -4265,8 +4265,22 @@ this is the fifth kernel built from this source base and the
>  date following it indicates the time the kernel was built.
>  .TP
>  .IR /proc/sys/kernel/threads-max " (since Linux 2.3.11)"
> +.\" The following is based on Documentation/sysctl/kernel.txt
>  This file specifies the system-wide limit on the number of
>  threads (tasks) that can be created on the system.
> +
> +The minimum value that can be written to threads-max is 20.
> +The maximum value that can be written to threads-max is given by the
> +constant
> +.B FUTEX_TID_MASK
> +(0x3fffffff).
> +If a value outside of this range is written to threads-max an error
> +.B EINVAL
> +occurs.
> +
> +The value written is checked against the available RAM pages.
> +If the thread structures would occupy too much (more than 1/8th)
> +of the available RAM pages, threads-max is reduced accordingly.
>  .TP
>  .IR /proc/sys/kernel/zero-paged " (PowerPC only) "
>  This file

Thanks. Applied. 

It's also important to not the kernel version that added these
range checks, I think. So I've added that info also.

Cheers,

Michael


-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
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