Daniel
Wed May 12 01:49:12 CDT 2004
Nice theory... That would explain a few things... I wonder if, after
grabbing a significant amount of memory, it grabs a further significant
amount when the first one fills up and *then* never frees either until *all*
of those suballocations are GC-able...
Hopefully some MS person will jump in to confirm the theories/speculations
that this thread contains...
In the mean time thanks for your insights... I'll dig further and post any
new findings (in the form of questions no doubt :-)
Cheers
Daniel
"Paul G. Tobey [eMVP]" <ptobey_no_spam@instrument_no_spam.com> wrote in
message news:uQYvI94NEHA.1616@TK2MSFTNGP12.phx.gbl...
> I can advance a theory about why GC doesn't return the memory to the
system,
> but I don't know for sure. It would be interesting to see if allocating a
> lot of things to the point where the GC grabs a significant amount of
extra
> RAM from the system and then releasing those allocations would return it
to
> the system. It may just be that the GC grabs a significant amount of RAM
by
> default (or at certain allocation sizes or something), and continues to
> manage that memory itself (I'm sure that would make allocations faster).
It
> seems like there would be some way to force release of everything not
> actually containing an active allocation, but maybe not. C++ does
something
> like this in the run-time library, by the way. When you do new enough,
the
> run-time will need more memory, so it will do a LocalAlloc() to grab some
> more and then sub-allocate that for the new requests. However, unless you
> deallocate *all* of those suballocations in that one block (which you
don't
> have any visibility into), it will never do a LocalFree()...
>
> Paul T.
>
> "Daniel Moth" <dmoth74@hotmail.com> wrote in message
> news:OSRHb24NEHA.268@TK2MSFTNGP11.phx.gbl...
> > Hmm... interesting...
> >
> > I suspect you are right about GetTotalMemory(false) returning the data
> items
> > only (which is what my leading question of my original email was trying
to
> > get confirmation to)...
> >
> > Since for the simple (8KB exe) CF app, the value C=1MB then we could
> deduct
> > that the JIT compiler and other standard memory allocations needed by
the
> > runtime are covered by 1MB [1]
> >
> > Based on [1] we are still missing (in my specific scenario) over 7MB,
> which
> > so far we think accounts for the code (both own (1MB of binaries) and
> > Microsoft's). It would be useful at this point to get definite
> confirmation
> > of this plus to understand the relationship between number of bytes of
> C#/VB
> > code versus number of bytes taken at runtime...
> >
> > I still find [1] itself a huge jump.
> >
> > My other question remains un-tackled.
> > > > 3) After a GC.Collect, GetTotalMemory diminishes but C remains
> constant.
> > > > Why?
> > Not only we should be able to observe the same reduction that
> GetTotalMemory
> > reports but since a collection may include pitching of jitted bytes I
> would
> > definitely expect it to affect C (the number of bytes returned by
> > GlobalMemoryStatus).
> >
> > Cheers
> > Daniel
> >
> >
> > "Paul G. Tobey [eMVP]" <ptobey_no_spam@instrument_no_spam.com> wrote in
> > message news:%23uaEBj4NEHA.1272@tk2msftngp13.phx.gbl...
> > > I would expect that GetTotalMemory( false ) would return the total
> dynamic
> > > (and maybe static), *data* memory allocations for your process, but it
> > might
> > > easily not include memory allocated by the run-time environment for
> things
> > > like the JIT compiler, the code itself for your program, as well as
the
> > > system class code, etc. That is, in C++, C would include the amount
of
> > RAM
> > > dedicated to the actual code for the loaded classes, while
> GetTotalMemory(
> > > false ) would likely only include those *data* items actually
allocated
> by
> > > your code via new().
> > >
> > > My comment about RAM filesystem, etc. was covered by your actions to
get
> a
> > > value for A.
> > >
> > > Paul T.
> > >
> > > "Daniel Moth" <dmoth74@hotmail.com> wrote in message
> > > news:%23t$EaX4NEHA.2716@tk2msftngp13.phx.gbl...
> > > > OK, sorry, when I said "no other apps" I meant no apps of mine
> (thought
> > > the
> > > > "taking in account memory used by the system" bit covered that)...
> > > >
> > > > In any case, if we open explorer pointing to the folder where the
exe
> > > > resides and then check the memory in use (from the memory panel) we
> get
> > a
> > > > value A. If we then launch our exe and go back to the panel we see a
> > value
> > > > B. If C=B-A, isn't it fair to say that C is the amount of bytes used
> by
> > > our
> > > > app/process?
> > > >
> > > > If not then please let me know what I am missing?
> > > >
> > > > If it is, then (some of) my original questions were:
> > > > 1) Why is C=9072KB when GetTotalMemory(false) returns 446KB
> > > > 2) How come the simplest CF app (8KB exe) shows C=over 1MB
> > > > 3) After a GC.Collect, GetTotalMemory diminishes but C remains
> constant.
> > > > Why?
> > > >
> > > > Cheers
> > > > Daniel
> > > >
> > > > PS
> > > > I am not positive I know what you mean by this:
> > > >
> > > > >>As I recall, the RAM filesystem is allocated by the file system
> > > > >> manager. It's possible that the memory that you have allocated
to
> > that
> > > > >> is
> > > > >> contributing a significant fraction of what you are seeing
> allocated.
> > > >
> > > > If you mean the size of my binaries they are 1MB in total so a long
> way
> > to
> > > > almost 9MB isn't it?
> > > >
> > > >
> > > >
> > > > "Paul G. Tobey [eMVP]" <ptobey_no_spam@instrument_no_spam.com> wrote
> in
> > > > message news:%23Vh$aq3NEHA.680@TK2MSFTNGP11.phx.gbl...
> > > > > There are *always* several applications running and they use a
fair
> > > amount
> > > > > of memory. The kernel (nk.exe), the windowing system (gwes.exe),
> the
> > > > device
> > > > > manager (device.exe), the file system manager (filesys.exe), etc.
> are
> > > all
> > > > in
> > > > > there. As I recall, the RAM filesystem is allocated by the file
> > system
> > > > > manager. It's possible that the memory that you have allocated to
> > that
> > > is
> > > > > contributing a significant fraction of what you are seeing
> allocated.
> > > > >
> > > > > Paul T.
> > > > >
> > > > > "Daniel Moth" <dmoth74@hotmail.com> wrote in message
> > > > > news:OGAvQb3NEHA.3420@TK2MSFTNGP11.phx.gbl...
> > > > > > Hi
> > > > > >
> > > > > > Hopefully someone can help me clarify some memory issues and in
> > > > particular
> > > > > > the difference between GetTotalMemory & GlobalMemoryStatus...
> > > > > >
> > > > > > Apparently GetTotalMemory(false) retrieves the number of bytes
> > > currently
> > > > > > thought to be allocated. I assume the bytes returned reflect
only
> > the
> > > > > > managed bytes(objects) that *my* managed code has allocated, is
> that
> > > > > > correct? In other words if I have PInvoke calls that allocate
> memory
> > > > that
> > > > > > would not be included, right? Is there anything else
> GetTotalMemory
> > > > > excludes
> > > > > > that one would assume is included?
> > > > > >
> > > > > > I observe a large difference between what GetTotalMemory returns
> and
> > > > what
> > > > > > GlobalMemoryStatus reports (taking in account the memory used by
> the
> > > > > system.
> > > > > > No other apps running). I am guessing this is because the
> > > > > GlobalMemoryStatus
> > > > > > includes the JITed code as used memory whereas GetTotalMemory
> > doesn't;
> > > > is
> > > > > > that correct? Still the discrepancy is large so there must be
> other
> > > > > factors
> > > > > > that I am not aware of... For example when GetTotalMemory
returns
> > > 446KB
> > > > > > GlobalMemoryStatus (or indeed the memory control panel or even
the
> > > > remote
> > > > > > system info from eVC) shows 9072KB. What extra bytes is it
> > including?
> > > > > >
> > > > > > It seems even the simplest CF app (8KB exe) consumes over 1MB of
> > > memory.
> > > > > Is
> > > > > > that right or is there some flaw in my approach? Also GC.Collect
> > > affect
> > > > > the
> > > > > > results of GetTotalMemory but not the results of
> > GlobalMemoryStatus...
> > > > is
> > > > > > that in line with your observations?
> > > > > >
> > > > > > Note that when the above results are observed, I then leave the
> > > unit/app
> > > > > > running for at least 1 hour (in idle mode) and the results
remain
> > the
> > > > > > same... I have also used the slider to effectively force a
memory
> > load
> > > > of
> > > > > > over 95%...
> > > > > >
> > > > > > Cheers
> > > > > > Daniel
> > > > > >
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