On Fri, 1 Apr 2005, Matthew Dillon wrote:
:The use of the XMM registers is a cpu optimization. Modern CPUs,
:especially AMD Athlon and Opterons, are more efficient with 128 bit
:moves then with 64 bit moves. I experimented with all sorts of
:configurations, including the use of
On Thu, 31 Mar 2005, Matthew Dillon wrote:
I didn't mean to get into the kernel's use of the FPU, but...
All I really did was implement a comment that DG had made many years
ago in the PCB structure about making the FPU save area a pointer rather
then hardwiring it into the PCB.
ISTR
:The use of the XMM registers is a cpu optimization. Modern CPUs,
:especially AMD Athlon and Opterons, are more efficient with 128 bit
:moves then with 64 bit moves. I experimented with all sorts of
:configurations, including the use of special data caching instructions,
:
Here is the core of the FPU setup and restoration code for the kernel
bcopy in DragonFly, from i386/bcopy.s.
DragonFly uses the TD_SAVEFPU-is-a-pointer method that was outlined in
the original comment in the FreeBSD code. I further enhance the
algorithm to guarentee that the
On Thu, 2005-Mar-31 17:17:58 +1000, Bruce Evans wrote:
On the i386 (and probably most other CPUs), you can place the FPU into
am unavailable state. This means that any attempt to use it will
trigger a trap. The kernel will then restore FPU state and return.
On a normal system call, if the FPU
On Wed, 30 Mar 2005, David Schultz wrote:
On Wed, Mar 30, 2005, Peter Jeremy wrote:
On Tue, 2005-Mar-29 22:57:28 -0500, jason henson wrote:
Later in that thread they discuss skipping the restore state to make
things faster. The minimum buffer size they say this will be good for
is between 2-4k.
On Thu, 31 Mar 2005, Peter Jeremy wrote:
On Thu, 2005-Mar-31 17:17:58 +1000, Bruce Evans wrote:
I still
think fully lazy switching (c2) is the best general method.
I think it depends on the FP workload. It's a definite win if there
is exactly one FP thread - in this case the FPU state never
All I really did was implement a comment that DG had made many years
ago in the PCB structure about making the FPU save area a pointer rather
then hardwiring it into the PCB.
This greatly reduces the complexity of work required to allow
the kernel to 'borrow' the FPU. It
On Tue, 2005-Mar-29 22:57:28 -0500, jason henson wrote:
Later in that thread they discuss skipping the restore state to make
things faster. The minimum buffer size they say this will be good for
is between 2-4k. Does this make sense, or am I showing my ignorance?
On Wed, Mar 30, 2005, Peter Jeremy wrote:
On Tue, 2005-Mar-29 22:57:28 -0500, jason henson wrote:
Later in that thread they discuss skipping the restore state to make
things faster. The minimum buffer size they say this will be good for
is between 2-4k. Does this make sense, or am I
On Mon, 2005-Mar-28 23:23:19 -0800, David Leimbach wrote:
meant to send this to the list too... sorry
Are you implying DragonFly uses FPU/SIMD? For that matter does any kernel?
I believe it does use SIMD for some of it's fast memcopy stuff for
it's messaging system
actually. I remember Matt
On Tue, Mar 29, 2005 at 09:11:07PM +1000, Peter Jeremy wrote:
That's almost a year ago and specifically for the amd64. Does anyone
know what the results were?
I had a quick dig around on cvsweb this morning:
On Tue, Mar 29, 2005 at 02:12:53PM +0100, David Malone wrote:
On Tue, Mar 29, 2005 at 09:11:07PM +1000, Peter Jeremy wrote:
That's almost a year ago and specifically for the amd64. Does anyone
know what the results were?
I had a quick dig around on cvsweb this morning:
On Tue, 29 Mar 2005 21:11:07 +1000, Peter Jeremy
[EMAIL PROTECTED] wrote:
On Mon, 2005-Mar-28 23:23:19 -0800, David Leimbach wrote:
meant to send this to the list too... sorry
Are you implying DragonFly uses FPU/SIMD? For that matter does any kernel?
I believe it does use SIMD for some of
Peter Jeremy wrote:
On Mon, 2005-Mar-28 23:23:19 -0800, David Leimbach wrote:
meant to send this to the list too... sorry
Are you implying DragonFly uses FPU/SIMD? For that matter does any kernel?
I believe it does use SIMD for some of it's fast memcopy stuff for
it's messaging
meant to send this to the list too... sorry
Are you implying DragonFly uses FPU/SIMD? For that matter does any kernel?
I believe it does use SIMD for some of it's fast memcopy stuff for
it's messaging system
actually. I remember Matt saying he was working on it.
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