Messages in this thread | | | From | Goswin von Brederlow <> | Subject | Re: [00/41] Large Blocksize Support V7 (adds memmap support) | Date | Sun, 23 Sep 2007 08:56:39 +0200 |
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Andrea Arcangeli <andrea@suse.de> writes:
> On Mon, Sep 17, 2007 at 12:56:07AM +0200, Goswin von Brederlow wrote: >> When has free ever given any usefull "free" number? I can perfectly >> fine allocate another gigabyte of memory despide free saing 25MB. But >> that is because I know that the buffer/cached are not locked in. > > Well, as you said you know that buffer/cached are not locked in. If > /proc/meminfo would be rubbish like you seem to imply in the first > line, why would we ever bother to export that information and even > waste time writing a binary that parse it for admins?
As a user I know it because I didn't put a kernel source into /tmp. A programm can't reasonably know that.
>> On the other hand 1GB can instantly vanish when I start a xen domain >> and anything relying on the free value would loose. > > Actually you better check meminfo or free before starting a 1G of Xen!!
Xen has its own memory pool and can quite agressively reclaim memory from dom0 when needed. I just ment to say that the number in /proc/meminfo can change in a second so it is not much use knowing what it said last minute.
>> The only sensible thing for an application concerned with swapping is >> to whatch the swapping and then reduce itself. Not the amount >> free. Although I wish there were some kernel interface to get a >> preasure value of how valuable free pages would be right now. I would >> like that for fuse so a userspace filesystem can do caching without >> cripling the kernel. > > Repeated drop caches + free can help.
I would kill any programm that does that to find out how much free ram the system has.
MfG Goswin - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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