[Disksim-users] Request arrival rate

[Nobody Nobody Nobody]

Not sure if commenting out is a good idea. I tried to increase the MAX_QUEUE_LENGTH value. But it appears that disksim either hangs or takes a really really long time to finish if I do this. You can see the offending while loop by attaching a debugger to it. Basically, the loop seems to be making progress, but it's hard to say for sure since it seems to run forever.

--- On Mon, 8/3/09, David Maung <dmaung at earthlink.net> wrote:

From: David Maung <dmaung at earthlink.net>
Subject: Re: [Disksim-users] Request arrival rate
To: disksim-users at ece.cmu.edu
Date: Monday, August 3, 2009, 2:12 PM


> The simulation stops with a message "Stopping simulation because of
saturation"

I ran into this error myself.  It is a hard limit.  In disksim_lororg.c, you
can find the offending code as:

   if (currlogorg->stat.outstanding >= MAX_QUEUE_LENGTH) {
      fprintf(stderr,"Stopping simulation because of saturation: simtime %f,
totalreqs %d\n", simtime, disksim->totalreqs);
      fflush(stderr);
      fprintf (outputfile, "Stopping simulation because of saturation:
simtime %f, totalreqs %d\n", simtime, disksim->totalreqs);
      fprintf (outputfile, "last request:  dev=%d, blk=%d, cnt=%d, %d
(R==1)\n",curr->devno, curr->blkno, curr->bcount, (curr->flags & READ));
      disksim_simstop();
   }

MAX_QUEUE_LENGTH is 10000 and is not based on any underlying cache
configuration or anything.  For example, I have configured a memory cache of
8192 blocks, but outstanding requests can still exceed 10000, perhaps due to
multiple requests for the same blocks, etc.  I would be inclined to comment
out this code, if, as in my case, you actually find it to be invalid for
your given configuration.

David Maung


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