on 3/7/12 11:20 AMBruce Walker wrote
On Wed, Mar 7, 2012 at 11:41 AM, Godfrey DiGiorgi<[email protected]> wrote:
HOWEVER, everything continues to work well. When I exit LR, within a
few moments the RAM is 50% green again. The fact that the system is
paging doesn't stop it from operating correctly and without
hesitation. Is your system acting aberrantly, aside from what you see
in Activity Monitor? I normally don't have Activity Monitor active as
I have not found much need to investigate and analyze memory and cpu
operations most of the time.
The reason I have Activity Monitor up so often is to give me an early
warning that resources are getting low and it's going to start paging
and becoming too sluggish to endure.
note that Activity Monitor puts a bit of a CPU load on your system, especially
if you have only one or two cores
The system is otherwise working fine, as fine as it can be with no
remaining RAM. It recovers right away when I exit from Lr -- all the
RAM that Lr was hogging is returned to the pool. What invariably
causes it to hesitate and generally become a slug is that Lr can't get
any additional space without VM paging. Paging is slow, of course,
because it's off a disk.
first of all, free RAM is wasted RAM, so you should never worry that "all your
RAM is used up"; virtual memory, even lots of it, is also not a problem if it
just sits there; what will slow things down is a high rate of paging, either on
a continuous basis, or when it occurs just as you are trying to interact with
the computer; the latter is what gets most people's attention, as switching
apps will often trigger it
there are some types of paging that are normal and unavoidable, such as when a
file is opened and it is mapped to memory; it's paging to and from swap — both
at once — that causes the biggest slowdown; a quick way to monitor VM activity
is to leave a terminal window open with the command "vm_stat 1" running; ignore
the cumulative row beneath each header row; in the other rows, the last two
columns will be non-zero when paging, and you can easily correlate the
magnitude of the numbers with perceived slowness (on my system, this monitoring
takes much less CPU than Activity Monitor)
And then to top it off, Time Machine always kicks in at the most
inopportune moment and starts trying to take more RAM *and* making all
the drives busy.
i personally do not like Time Machine kicking in every hour; with Time Machine
Scheduler you can control the schedule (i have it kick in overnight):
<http://www.klieme.com/TimeMachineScheduler.html>
Perhaps the use of 6G RAM instead of the more commonly used 4G and 8G
configurations is itself the issue. Perhaps the memory controller
isn't as efficient in scavenging and doing reallocations with that
memory size. [...]
It was outrageously bad for me before I increased from 4 Gig to 6 Gig.
So it works better now, but is still darned annoying.
a 6GB configuration poses no special problems for the VM system, but if your
system can use 8GB or more, and you have performance issues, then a RAM upgrade
will certainly help
Indeed that's what I end up doing -- stopping and restarting the
trouble-prone apps -- but I was lamenting the necessity to do that. If
Lr handled RAM better, it wouldn't keep claiming more and more of it
while working; it would release some when done with it.
any app will "release" all of its memory when quit, but you may not see an
immediate impact on the amount of VM in use, as any VM pages used by app X
aren't hurting anything when app X is not active, so the system is in no hurry
to reclaim them; it's only a problem when you are short on space; i do
sometimes quit Aperture, Chrome, and Safari; Chrome is the worst as dozens of
renderers
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