I doubt that very much, or we wouldn't have variable speed fans. I've
monitored CPU temperature when doing compilations; it goes up
significantly. That suggests that the CPU is drawing more power at
such times.
Of course, there's another implication -- if the CPU isn't using the
power, the draw from the power line is less, which means that much less
electricity is being used.
--Steve Bellovin, http://www.research.att.com/~smb
I doubt that very much, or we wouldn't have variable speed fans. I've
monitored CPU temperature when doing compilations; it goes up
significantly. That suggests that the CPU is drawing more power at
such times.
I don't doubt what you are saying. However, I did say, "in the grand scheme of things", meaning that the heat given off by the CPU, and change thereof, relative to the constant heat given off by the rotation of hard drives, the heat given off by the power supplies, etc., is still small.
Of course, there's another implication -- if the CPU isn't using the
power, the draw from the power line is less, which means that much less
electricity is being used.
An important point, but I still bet relatively small.
It's going to be a busy weekend at the Rubenstein Lab (aka, my garage) this weekend; I'll post results to my findings.
-- Alex Rubenstein, AR97, K2AHR, alex@nac.net, latency, Al Reuben --
-- Net Access Corporation, 800-NET-ME-36, http://www.nac.net --
Steven M. Bellovin wrote:
Hello,
I've done quite a bit of studyin power usage and such in datacenters over the last year or so.
I'm looking for information on energy consumption vs percent utilization. In
other words if your datacenter consumes 720 MWh per month, yet on average your servers are 98% underutilized, you are wasting a lot of energy (a hot topic these days). Does anyone here have any real data on this?
I've never done a study on power used vs. CPU utilization, but my guess is that the heat generated from a PC remains fairly constant -- in the grand scheme of things -- no matter what your utilization is.
I doubt that very much, or we wouldn't have variable speed fans. I've monitored CPU temperature when doing compilations; it goes up significantly. That suggests that the CPU is drawing more power at such times.
From running a Colo in a place with ridiculus high electricity engery
costs (Zurich/Switzerland) I can tell you that the energy consuption
of routers/telco (70%) and servers (30%) changes changes significantly
throughout the day. It pretty much follows the traffic graph. There
is a solid base load just because the stuff is powered up and from there
it goes up as much as 20-30% depending on the routing/computing load of
the boxes. To simplify things you can say that per packet you have that
many "mWh" (milli-Watt-hours) per packet switched/routed or http requests
answered over the base load. I haven't tried to calulate how much energy
routing a packet on a Cisco 12k or Juniper M40 cost though. Would be
very interesting if someone (student) could do that calculation.
From running a Colo in a place with ridiculus high electricity engery
costs (Zurich/Switzerland) I can tell you that the energy consuption
of routers/telco (70%) and servers (30%) changes changes significantly
throughout the day. It pretty much follows the traffic graph. There
is a solid base load just because the stuff is powered up and from there
it goes up as much as 20-30% depending on the routing/computing load of
the boxes. To simplify things you can say that per packet you have that
many "mWh" (milli-Watt-hours) per packet switched/routed or http requests
answered over the base load. I haven't tried to calulate how much energy
routing a packet on a Cisco 12k or Juniper M40 cost though. Would be
very interesting if someone (student) could do that calculation.
the same variation between night and day here - but from our point of view
the consumption of the air-pack's are making the differences during the day
... traffic-graph and outside temperature-graphs show more or less the same
up and down. Would we interesting to have separate values for the power
consumption between server-equipment and air-co ...
Greetings
Nik
Nik Hug wrote:
From: "Andre Oppermann"
From running a Colo in a place with ridiculus high electricity engery
costs (Zurich/Switzerland) I can tell you that the energy consuption
of routers/telco (70%) and servers (30%) changes changes significantly
throughout the day. It pretty much follows the traffic graph. There
is a solid base load just because the stuff is powered up and from there
it goes up as much as 20-30% depending on the routing/computing load of
the boxes. To simplify things you can say that per packet you have that
many "mWh" (milli-Watt-hours) per packet switched/routed or http requests
answered over the base load. I haven't tried to calulate how much energy
routing a packet on a Cisco 12k or Juniper M40 cost though. Would be
very interesting if someone (student) could do that calculation.the same variation between night and day here - but from our point of view
the consumption of the air-pack's are making the differences during the day
... traffic-graph and outside temperature-graphs show more or less the same
up and down. Would we interesting to have separate values for the power
consumption between server-equipment and air-co ...
In this case the air-co is not included. That is measured on a separate
circuit for which I don't have any figures ready.
Also note that especially high-end routers draw power load dependent. With
SONET/SDH stuff I haven't seen it. The reason is circuit switching. They
switch continuously the same amount of data.