Re: Mach VM management question

29 Jul 2002

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Hi guys,
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Thank you, Jim and Justin, for you kind replies
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I have a question regarding the VM management in Mach/Darwin.
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Since I don't like to reboot my mac, and since I use a lot of different
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applications, not at the same time, I'm surprised to see that the VM
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storage
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on my drives keeps going up, and never fall down.
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I have a tibook 500MHz, with 512MB of RAM, so I don't think that it's
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normal
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to have so many VM used at the same time on my machine :
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...[list of swap files deleted]...
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So, is there a way to tell the system to update the VM ? Or tell him to
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remove the unused VM swapfiles ?
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It happens automatically as the space is released.  But this is
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controlled by a user-level daemon process  (dynamic_pager).  If that
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got killed off somehow, you would neither free up any unused ones or
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allocate any new ones.  While I've never seen that happen, its
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something to look for in extremely weird cases.
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Ok, it's not that, since my VM goes up very easily ;-)

Thanks for the info though :-)
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Plus here's the output of my top :
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[... Top outpout deleted ...]
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So what is this kernel_tasks using 400M VSize ?
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The kernel allocates some virtual address space (space in submaps, not
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actual memory) for efficient future memory allocation and wiring later
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on. Top picks that up and reports it.  Kernel leaks would most likely
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cause a rise in wired memory.  With 512MB of memory, the 59.6MB of
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wired memory is not a major concern (some wired data structure counts
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scale up with amount of physical memory).
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There are uses of true virtual (pageable) memory within the kernel.
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Specifically, some of the (not currently in-use) texture maps for
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graphics acceleration are stored in kernel pageable memory.   And some
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(sent, but not-yet-received) Mach IPC data is stored in pagable kernel
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memory.
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There is no way to distinguish between over-commit virtual address
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space allocations in the kernel, and true pageable memory allocations
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using top.  So we can't tell how much of that 400MB of kernel virtual
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falls into each of the two categories above.  In fact, it isn't
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possible to tell that for any other task/process either.  Since your
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maximum "dirty virtual" memory size of ~1GB (7*76MB swap files + 512MB
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of physical memory) is less than the 1.69GB of all virtual allocations
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reported by top (even when you remove the 400MB of potentially unused
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space in the kernel), it may be correct.
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Thanks for the explanation
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Your top says there are 55 processes, and you only show 14 of them.  Is
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there anything else of interest in those other 41 processes?
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As an attachment, you'll find the outuput of "top -l -n 60"

All the processes are there. Unfortunately, I had to reboot after saving

this data, since AppleTalk went nuts ;-)

 BTW, yes, I have an MS Keyboard, and an MS Mouse, please don't blame me for

that ;-)

Pejvan

[demime 0.98b removed an attachment of type application/octet-stream which had a name of top-l-60.txt]

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Pejvan BEIGUI

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