:If RAM + swap can be more than 4GB, how does FreeBSD address swap on a
:32-bit machine? Does the kernel internally use a wider address space
:with some kind of translation to 32-bit space for programs and hardware
:that can't handle 64-bit addresses or does it not map swap into the
:address
Bernd Walter wrote:
On Fri, Jul 05, 2002 at 05:58:15PM -0700, Darren Pilgrim wrote:
If RAM + swap can be more than 4GB, how does FreeBSD address swap on a
32-bit machine? Does the kernel internally use a wider address space
The same way it does on every partitition: using block numbers.
On Sat, Jul 06, 2002 at 02:37:02PM -0700 I heard the voice of
Darren Pilgrim, and lo! it spake thus:
And you can have more than a single swap partition.
Up to four, so then the theoretical limit for swap is 8TB?
I hope not, since I have 6 of 'em. 4's just the default.
Do these
On Sat, Jul 06, 2002 at 02:37:02PM -0700, Darren Pilgrim wrote:
Bernd Walter wrote:
On Fri, Jul 05, 2002 at 05:58:15PM -0700, Darren Pilgrim wrote:
If RAM + swap can be more than 4GB, how does FreeBSD address swap on a
32-bit machine? Does the kernel internally use a wider address space
Bernd Walter wrote:
On Sat, Jul 06, 2002 at 02:37:02PM -0700, Darren Pilgrim wrote:
Bernd Walter wrote:
On Fri, Jul 05, 2002 at 05:58:15PM -0700, Darren Pilgrim wrote:
If RAM + swap can be more than 4GB, how does FreeBSD address swap on a
32-bit machine? Does the kernel internally
Darren Pilgrim wrote:
I thought the limit for filesystems was 2TB?
The Blocknumber is signed that gives:
2^31 * 512Bytes
Why sign the blocknumber? LBA uses an unsigned 32-bit integer,
allowing 2TB, and IIRC SCSI uses an unsigned integer as well (though I
can't remember if that one
On Sat, Jul 06, 2002 at 03:43:00PM -0700, Darren Pilgrim wrote:
Bernd Walter wrote:
On Sat, Jul 06, 2002 at 02:37:02PM -0700, Darren Pilgrim wrote:
Bernd Walter wrote:
On Fri, Jul 05, 2002 at 05:58:15PM -0700, Darren Pilgrim wrote:
If RAM + swap can be more than 4GB, how does
On Sat, Jul 06, 2002 at 04:01:18PM -0700, Terry Lambert wrote:
Darren Pilgrim wrote:
I thought the limit for filesystems was 2TB?
The Blocknumber is signed that gives:
2^31 * 512Bytes
Why sign the blocknumber? LBA uses an unsigned 32-bit integer,
allowing 2TB, and IIRC SCSI
:...
:
: Up to four, so then the theoretical limit for swap is 8TB?
:
:I hope not, since I have 6 of 'em. 4's just the default.
:
:
: Do these management structures grow as swap grows, or do they only
: change as the utilization increases?
:
:I believe they're pre-allocated, so it's the size
Negative block numbers are used by UFS to represent the indirect blocks
associated with a file, while positive block numbers represent the
contents of the file.
These are logical block numbers, which are fragment-sized (1K typically).
So, 2^31 x 1K = 2TB.
Physical block
On Sat, Jul 06, 2002 at 04:42:22PM -0700, Matthew Dillon wrote:
Negative block numbers are used by UFS to represent the indirect blocks
associated with a file, while positive block numbers represent the
contents of the file.
I never saw any negative block numbers in on-disc
:
:On Sat, Jul 06, 2002 at 04:42:22PM -0700, Matthew Dillon wrote:
: Negative block numbers are used by UFS to represent the indirect blocks
: associated with a file, while positive block numbers represent the
: contents of the file.
:
:I never saw any negative block numbers in
On Sun, Jul 07, 2002 at 02:10:19AM +0200, Bernd Walter wrote:
On Sat, Jul 06, 2002 at 04:42:22PM -0700, Matthew Dillon wrote:
Negative block numbers are used by UFS to represent the indirect blocks
associated with a file, while positive block numbers represent the
contents of
:
: Physical block numbers are 512-byte sized, with a range of 2^32
: in -stable. This also winds up being 2TB. So increasing the fragment
: size does not help in -stable.
:
: It's a proven fact that there is a 1T limit somewhere which was
: explained with physical block
In message [EMAIL PROTECTED], Bernd Walter writes:
I never saw any negative block numbers in on-disc structures.
Now I wonder if it was just hidden behind macros.
What is the reason to handle it that way?
Do you have some code reference for homework?
These logical block numbers are not stored on
On Sat, Jul 06, 2002 at 05:33:50PM -0700, Matthew Dillon wrote:
:
:On Sat, Jul 06, 2002 at 04:42:22PM -0700, Matthew Dillon wrote:
: Negative block numbers are used by UFS to represent the indirect blocks
: associated with a file, while positive block numbers represent the
:
Matthew Dillon wrote:
The nominal limit for swap space is around 14 GB due to limitations
in available KVM. There are three major limiting factors in the kernel:
* The swap bitmap eats 2 bits per page of swap. The bitmap is sized
to handle NSWAP (default 4) x
:Is NSWAP tied to the NSWAPDEV kernel option, or is it the actual number
:of active swap devices? If the prior, is setting NSWAPDEV to the
:actual number of swap devices a useful for improving memory usage? Is
:NSWAPDEV just a compile-time tunable, or is there a sysctl to do the
:same thing?
Thanks guys, for explaining the swap system to me. I have a good
understanding of how the system works now. I want to particularly
thank Matthew Dillon for taking the time to lay down the technical
details as he did. Being able to ask a question like this and get it
answered so well is what
If RAM + swap can be more than 4GB, how does FreeBSD address swap on a
32-bit machine? Does the kernel internally use a wider address space
with some kind of translation to 32-bit space for programs and hardware
that can't handle 64-bit addresses or does it not map swap into the
address space at
On Fri, Jul 05, 2002 at 05:58:15PM -0700, Darren Pilgrim wrote:
If RAM + swap can be more than 4GB, how does FreeBSD address swap on a
32-bit machine? Does the kernel internally use a wider address space
The same way it does on every partitition: using block numbers.
That way you can address
Darren Pilgrim wrote:
If RAM + swap can be more than 4GB, how does FreeBSD address swap on a
32-bit machine? Does the kernel internally use a wider address space
with some kind of translation to 32-bit space for programs and hardware
that can't handle 64-bit addresses or does it not map swap
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