.TH CPUPOWER\-SET "1" "22/02/2011" "" "cpupower Manual"
.SH NAME
cpupower\-set \- Set processor power related kernel or hardware configurations
.SH SYNOPSIS
.ft B
.B cpupower set [ \-b VAL ]


.SH DESCRIPTION
\fBcpupower set \fP sets kernel configurations or directly accesses hardware
registers affecting processor power saving policies.

Some options are platform wide, some affect single cores. By default values
are applied on all cores. How to modify single core configurations is
described in the cpupower(1) manpage in the \-\-cpu option section. Whether an
option affects the whole system or can be applied to individual cores is
described in the Options sections.

Use \fBcpupower info \fP to read out current settings and whether they are
supported on the system at all.

.SH Options
.PP
\-\-perf-bias, \-b
.RS 4
Sets a register on supported Intel processore which allows software to convey
its policy for the relative importance of performance versus energy savings to
the  processor.

The range of valid numbers is 0-15, where 0 is maximum
performance and 15 is maximum energy efficiency.

The processor uses this information in model-specific ways
when it must select trade-offs between performance and
energy efficiency.

This policy hint does not supersede Processor Performance states
(P-states) or CPU Idle power states (C-states), but allows
software to have influence where it would otherwise be unable
to express a preference.

For example, this setting may tell the hardware how
aggressively or conservatively to control frequency
in the "turbo range" above the explicitly OS-controlled
P-state frequency range.  It may also tell the hardware
how aggressively it should enter the OS requested C-states.

This option can be applied to individual cores only via the \-\-cpu option,
cpupower(1).

Setting the performance bias value on one CPU can modify the setting on
related CPUs as well (for example all CPUs on one socket), because of
hardware restrictions.
Use \fBcpupower -c all info -b\fP to verify.

This options needs the msr kernel driver (CONFIG_X86_MSR) loaded.
.RE

.SH "SEE ALSO"
cpupower-info(1), cpupower-monitor(1), powertop(1)
.PP
.SH AUTHORS
.nf
\-\-perf\-bias parts written by Len Brown <len.brown@intel.com>
Thomas Renninger <trenn@suse.de>
>
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<div class='path'>path: <a href='/cgit.cgi/linux/net-next.git/log/?id=71810db27c1c853b335675bee335d893bc3d324b'>root</a>/<a href='/cgit.cgi/linux/net-next.git/log/sound?id=71810db27c1c853b335675bee335d893bc3d324b'>sound</a>/<a href='/cgit.cgi/linux/net-next.git/log/sound/ppc?id=71810db27c1c853b335675bee335d893bc3d324b'>ppc</a>/<a href='/cgit.cgi/linux/net-next.git/log/sound/ppc/daca.c?id=71810db27c1c853b335675bee335d893bc3d324b'>daca.c</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/cgit.cgi/linux/net-next.git/log/sound/ppc/daca.c?id=71810db27c1c853b335675bee335d893bc3d324b&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th><th class='left'>Files</th><th class='left'>Lines</th></tr>
ext.git/log/include/net/ipv6.h?id=37a7ea4a9b81f6a864c10a7cb0b96458df5310a3'>Collapse</a>)</th><th class='left'>Author</th><th class='left'>Files</th><th class='left'>Lines</th></tr>
<tr class='logheader'><td><span title='2017-01-31 13:16:59 -0500'>2017-01-31</span></td><td class='logsubject'><a href='/cgit.cgi/linux/net-next.git/commit/include/net/ipv6.h?id=90427ef5d2a4b9a24079889bf16afdcdaebc4240'>ipv6: fix flow labels when the traffic class is non-0</a></td><td>Dimitris Michailidis</td><td>1</td><td><span class='deletions'>-0</span>/<span class='insertions'>+5</span></td></tr>
<tr class='nohover-highlight'><td/><td colspan='5' class='logmsg'>
ip6_make_flowlabel() determines the flow label for IPv6 packets. It's
supposed to be passed a flow label, which it returns as is if non-0 and
in some other cases, otherwise it calculates a new value.

The problem is callers often pass a flowi6.flowlabel, which may also
contain traffic class bits. If the traffic class is non-0
ip6_make_flowlabel() mistakes the non-0 it gets as a flow label and
returns the whole thing. Thus it can return a 'flow label' longer than
20b and the low 20b of that is typically 0 resulting in packets with 0
label. Moreover, different packets of a flow may be labeled differently.
For a TCP flow with ECN non-payload and payload packets get different
labels as exemplified by this pair of consecutive packets:

(pure ACK)
Internet Protocol Version 6, Src: 2002:af5:11a3::, Dst: 2002:af5:11a2::
    0110 .... = Version: 6
    .... 0000 0000 .... .... .... .... .... = Traffic Class: 0x00 (DSCP: CS0, ECN: Not-ECT)
        .... 0000 00.. .... .... .... .... .... = Differentiated Services Codepoint: Default (0)
        .... .... ..00 .... .... .... .... .... = Explicit Congestion Notification: Not ECN-Capable Transport (0)
    .... .... .... 0001 1100 1110 0100 1001 = Flow Label: 0x1ce49
    Payload Length: 32
    Next Header: TCP (6)

(payload)
Internet Protocol Version 6, Src: 2002:af5:11a3::, Dst: 2002:af5:11a2::
    0110 .... = Version: 6
    .... 0000 0010 .... .... .... .... .... = Traffic Class: 0x02 (DSCP: CS0, ECN: ECT(0))
        .... 0000 00.. .... .... .... .... .... = Differentiated Services Codepoint: Default (0)
        .... .... ..10 .... .... .... .... .... = Explicit Congestion Notification: ECN-Capable Transport codepoint '10' (2)
    .... .... .... 0000 0000 0000 0000 0000 = Flow Label: 0x00000
    Payload Length: 688
    Next Header: TCP (6)

This patch allows ip6_make_flowlabel() to be passed more than just a
flow label and has it extract the part it really wants. This was simpler
than modifying the callers. With this patch packets like the above become

Internet Protocol Version 6, Src: 2002:af5:11a3::, Dst: 2002:af5:11a2::
    0110 .... = Version: 6
    .... 0000 0000 .... .... .... .... .... = Traffic Class: 0x00 (DSCP: CS0, ECN: Not-ECT)
        .... 0000 00.. .... .... .... .... .... = Differentiated Services Codepoint: Default (0)
        .... .... ..00 .... .... .... .... .... = Explicit Congestion Notification: Not ECN-Capable Transport (0)
    .... .... .... 1010 1111 1010 0101 1110 = Flow Label: 0xafa5e
    Payload Length: 32
    Next Header: TCP (6)

Internet Protocol Version 6, Src: 2002:af5:11a3::, Dst: 2002:af5:11a2::
    0110 .... = Version: 6
    .... 0000 0010 .... .... .... .... .... = Traffic Class: 0x02 (DSCP: CS0, ECN: ECT(0))
        .... 0000 00.. .... .... .... .... .... = Differentiated Services Codepoint: Default (0)
        .... .... ..10 .... .... .... .... .... = Explicit Congestion Notification: ECN-Capable Transport codepoint '10' (2)
    .... .... .... 1010 1111 1010 0101 1110 = Flow Label: 0xafa5e
    Payload Length: 688
    Next Header: TCP (6)

Signed-off-by: Dimitris Michailidis &lt;dmichail@google.com&gt;
Acked-by: Eric Dumazet &lt;edumazet@google.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;


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