Re: Where do you put your swap partition?
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On 01/23/08 14:49, Mike Kuhar wrote:
>
> Subject: Re: Where do you put your swap partition?
>
> On 2008-01-23T15:17:29-0500, Mike Kuhar wrote:
>> Most things stated in this chain are true. But a couple notes. First, a
>> swap partition is not the same as a normal partition, i.e. ext2 or ext2.
>> That is, in Window's speak, it's not formatted. Process chunks that are
>> swapped in and out of swap does not go through the filesystem manager.
> The
>> kernel directly manages that space. It treats that disk space as a raw
>> disk. Much faster than going through the read/writes to a normal file.
> You
>> can create a swap file, but that's much slower than swap space, because it
>> has to go through the file system.
>
> These two threads do not suggest there is any significant performance
> difference between swap file and swap partitions:
> http://lkml.org/lkml/2005/6/28/427
> http://groups.google.com/group/cwelug/browse_thread/thread/c7d44b3d414f7da2
>
> ----------------------------------
>
> If that's meaningful for you, than by all means use a swap file.
Denying *direct* evidence that swap file is faster? Are you sure
you aren't a Young Earth Creationist?
> But going
> through the filesystem is never the fastest way to disk.
I know this is /ipse dixit/ (appeal to authority), but when Andrew
Morton says "The kernel generates a map of swap offset -> disk
blocks at swapon time and from then on uses that map to perform swap
I/O directly against the underlying disk queue, bypassing all
caching, metadata and filesystem code.", I believe him.
> If that were the
> case, then Oracle would never offer the ability to use a disk in raw mode
> for speed.
Oracle must support a *wide* variety of OSs, and has had to do so
for many years.
> You don't have to configure this way, but it is offered for
> speed. But then again, a home user never taxes a system like a business
> system. If you are more comfortable using a swap file, then use it.
- --
Ron Johnson, Jr.
Jefferson LA USA
"I'm not a vegetarian because I love animals, I'm a vegetarian
because I hate vegetables!"
unknown
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