From mboxrd@z Thu Jan 1 00:00:00 1970 Content-Type: multipart/mixed; boundary="===============1174829338764822066==" MIME-Version: 1.0 From: Paul E. McKenney To: lkp@lists.01.org Subject: Re: [rcu] 7c66b15f870: +1.8% turbostat.Pkg_W Date: Wed, 25 Jun 2014 21:00:47 -0700 Message-ID: <20140626040047.GU4603@linux.vnet.ibm.com> In-Reply-To: <20140626021809.GA14734@localhost> List-Id: --===============1174829338764822066== Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable On Thu, Jun 26, 2014 at 10:18:09AM +0800, Fengguang Wu wrote: > On Wed, Jun 25, 2014 at 07:10:23PM -0700, Paul E. McKenney wrote: > > On Thu, Jun 26, 2014 at 09:33:08AM +0800, Fengguang Wu wrote: > > > Hi Paul, > > > = > > > We noticed increased power consumption in our internal merge commit. > > > It's not a direct evidence, however in the hope you can see any > > > obvious clues. :) > > = > > Hello, Fengguang, > > = > > This particular branch is obsolete, and has been replaced by commit > > 4a81e8328d37 (Reduce overhead of cond_resched() checks for RCU). > = > Ah great, we happen to have more direct numbers for that patch. :) > = > > Just out of curiosity, how do you measure the power consumption? > = > It's read by the turbostat tool, from CPU MSRs: OK, thank you for the info. I would trust a physical power-line sensor more, but then again, I am picky. ;-) Thanx, Paul > commit 889facbee3e67dbc8eb29d8ee7fd66d33a647bfc > Author: Len Brown > AuthorDate: Thu Nov 8 00:48:57 2012 -0500 > Commit: Len Brown > CommitDate: Fri Nov 30 01:09:44 2012 -0500 > = > tools/power turbostat: v3.0: monitor Watts and Temperature > = > Show power in Watts and temperature in Celsius > when hardware support is present. > = > Intel's Sandy Bridge and Ivy Bridge processor generations support RAPL > (Run-Time-Average-Power-Limiting). Per the Intel SDM > (Intel=C2=AE 64 and IA-32 Architectures Software Developer Manual) > RAPL provides hardware energy counters and power control MSRs > (Model Specific Registers). RAPL MSRs are designed primarily > as a method to implement power capping. However, they are useful > for monitoring system power whether or not power capping is used. > = > In addition, Turbostat now shows temperature from DTS > (Digital Thermal Sensor) and PTM (Package Thermal Monitor) hardware, > if present. > = > As before, turbostat reads MSRs, and never writes MSRs. > = > New columns are present in turbostat output: > = > The Pkg_W column shows Watts for each package (socket) in the system. > On multi-socket systems, the system summary on the 1st row shows the = sum > for all sockets together. > = > The Cor_W column shows Watts due to processors cores. > Note that Core_W is included in Pkg_W. > = > The optional GFX_W column shows Watts due to the graphics "un-core". > Note that GFX_W is included in Pkg_W. > = > The optional RAM_W column on server processors shows Watts due to DRA= M DIMMS. > As DRAM DIMMs are outside the processor package, RAM_W is not include= d in Pkg_W. > = > The optional PKG_% and RAM_% columns on server processors shows the %= of time > in the measurement interval that RAPL power limiting is in effect on = the > package and on DRAM. > = > Note that the RAPL energy counters have some limitations. > = > First, hardware updates the counters about once every milli-second. > This is fine for typical turbostat measurement intervals > 1 sec. > However, when turbostat is used to measure events that approach > 1ms, the counters are less useful. > = > Second, the 32-bit energy counters are subject to wrapping. > For example, a counter incrementing 15 micro-Joule units > on a 130 Watt TDP server processor could (in theory) > roll over in about 9 minutes. Turbostat detects and handles > up to 1 counter overflow per measurement interval. > But when the measurement interval exceeds the guaranteed > counter range, we can't detect if more than 1 overflow occured. > So in this case turbostat indicates that the results are > in question by replacing the fractional part of the Watts > in the output with "**": > = > Pkg_W Cor_W GFX_W > 3** 0** 0** > = > Third, the RAPL counters are energy (Joule) counters -- they sum up > weighted events in the package to estimate energy consumed. They are > not analong power (Watt) meters. In practice, they tend to under-cou= nt > because they don't cover every possible use of energy in the package. > The accuracy of the RAPL counters will vary between product generatio= ns, > and between SKU's in the same product generation, and with temperatur= e. > = > turbostat's -v (verbose) option now displays more power and thermal c= onfiguration > information -- as shown on the turbostat.8 manual page. > For example, it now displays the Package and DRAM Thermal Design Powe= r (TDP): > = > cpu0: MSR_PKG_POWER_INFO: 0x2f064001980410 (130 W TDP, RAPL 51 - 200 = W, 0.045898 sec.) > cpu0: MSR_DRAM_POWER_INFO,: 0x28025800780118 (35 W TDP, RAPL 15 - 75 = W, 0.039062 sec.) > cpu8: MSR_PKG_POWER_INFO: 0x2f064001980410 (130 W TDP, RAPL 51 - 200 = W, 0.045898 sec.) > cpu8: MSR_DRAM_POWER_INFO,: 0x28025800780118 (35 W TDP, RAPL 15 - 75 = W, 0.039062 sec.) > = > Signed-off-by: Len Brown > --- > tools/power/x86/turbostat/turbostat.8 | 103 ++++-- > tools/power/x86/turbostat/turbostat.c | 643 ++++++++++++++++++++++++++++= ++++-- > 2 files changed, 690 insertions(+), 56 deletions(-) > = --===============1174829338764822066==--