In comp.os.linux.advocacy, Erik Funkenbusch
<erik@xxxxxxxxxxxxxxxxxxxxxx>
wrote
on Thu, 8 Feb 2007 18:07:23 -0600
<p2iode7xgzos.dlg@xxxxxxxxxxxxxxx>:
> On Thu, 8 Feb 2007 15:39:07 -0800, The Ghost In The Machine wrote:
>
>> In comp.os.linux.advocacy, Erik Funkenbusch
>> <erik@xxxxxxxxxxxxxxxxxxxxxx>
>> wrote
>> on Thu, 8 Feb 2007 16:31:49 -0600
>> <x522xnn5tgqk$.dlg@xxxxxxxxxxxxxxx>:
>>> On Thu, 08 Feb 2007 23:07:42 +0100, Peter Köhlmann wrote:
>>>
>>>> Erik Funkenbusch wrote:
>>>>
>>>>> On Thu, 08 Feb 2007 18:45:17 +0000, Roy Schestowitz wrote:
>>>>>
>>>>>> Analysis: Vista's Ready Boost is no match for RAM
>>>>>>
>>>>>> ,----[ Quote ]
>>>>>>| There's a new way to enhance your cache in Vista - simply plug in
>>>>>>| your Flash memory stick. But how much performance gain can you
>>>>>>| really expect? TG Daily ran an average PC through a benchmark
>>>>>>| parcours and discovered that the old rules still apply: There
>>>>>>| is no substitute for an adequate amount of system memory. Period.
>>>>>> `----
>>>>>>
>>>>>> http://tomshardware.co.uk/2007/02/08/analysis_vista_ready_boost/
>>>>>
>>>>> Of course it's not a substitute, that's why is a much cheaper alternative.
>>>>>
>>>>> 2GB of RAM will cost you around $200-$350 but a 2GB Flash disk is only
>>>>> $16.
>>>>
>>>> Yes. And it is only about as fast a harddisk
>>>> And has severely limited lifespan if written too often
>>>
>>> They have a sustained data transfer rate of a hard disk, but they have a
>>> 0ms seek time, which is HUGE. Further, the lifespan of writes on Flash
>>> drives has increased exponentially, and isn't a problem anymore. Finally,
>>> Vista doesn't constantly write to it. It writes once, and updates
>>> occasionally when your common usage chages, so even if that were true
>>> anymore it's not a factor.
>>>
>>>> Does not really make it that hot deal, it seems
>>>
>>> If you haven't got $200 it's definately a hot deal.
>>
>> And the difference between this capability of Vista and doing
>>
>> <insert stick>
>> # mkswap /dev/sdb1
>> # swapon /dev/sdb1
>>
>> is...?
>>
>> Granted, the Linux variant is not quite as automatic.
>
> Umm.. everything? It's not putting swap on a ram disk, that would be
> stupid. It's disk cache.
And the difference between putting swap on a USB-based
disk stick and a USB-based disk stick cache is ...?
In case you've missed OS 101 :-) , programs allocate
virtual memory. The kernel (Vista or Linux) tracks this
allocation, but the memory desired may not be in real RAM
any more than a desert-created mirage is really there.
Fortunately, if the program requests that memory, the
kernel, unlike the desert, can at least fetch it from
somewhere.
If there's already too much in RAM the kernel has to do
some housecleaning, throwing some of the unneeded pages
into the attic -- swap.
If the program needs a page from the attic the kernel
will then retrieve it therefrom, possibly putting someone
else's page into the attic as it does so -- which can lead
to thrashing.
(It is possible for a program to request a page from a
file as well, after using mmap() or mmap2(). These are
side issues.)
I'll admit caching disk by using a pseudo-disk device
is an interesting idea. However, I fail to see any real
performance improvement possibilities.
(It would be interesting to define a minimum disk cache
in Linux as a tunable parameter. The tradeoff of course
would be that the more physical RAM is dedicated to disk
cache, the sooner the system will start to swap as its
load increases. Some of that swap could be thrown onto
the USB stick, and Linux does support swap prioritization.)
--
#191, ewill3@xxxxxxxxxxxxx
Is it cheaper to learn Linux, or to hire someone
to fix your Windows problems?
--
Posted via a free Usenet account from http://www.teranews.com
|
|
