* [take3 0/5] d80211: remove bitfields from include/net/d80211.h
@ 2006-10-25 18:42 David Kimdon
2006-10-25 19:01 ` Jeff Garzik
0 siblings, 1 reply; 6+ messages in thread
From: David Kimdon @ 2006-10-25 18:42 UTC (permalink / raw)
To: netdev; +Cc: John W. Linville, Jiri Benc
Continue d80211 bitfield removal. In general, compilers have
difficulty generating efficient code for bitfields. This patchset
removes all bitfields from include/net/d80211.h.
I converted the 1 bit bitfields into a bit in a u32/u16 or u8 flags
structure member. Larger bitfields I converted into their
u8/u16/whatever equivalent.
This should be a no-op from a functionality standpoint.
All tests using gcc 4.1.2.
The size of structures where bitfields were removed is identical
patched and unpatched. All object text size is either slightly
smaller after the patch, or unchanged (bss and data are all
unchanged). With all d80211 drivers compiled in the patched vmlinux
is 1232 bytes smaller.
Changes from take2:
Refresh to apply to current wireless-dev.
Changes from take1:
Update rt2500usb.c and rt73usb.c drivers based on the new structures.
Changes from take0:
Update the patches to apply on top of the following patches:
d80211: remove unused Super AG definitions, purge comment
(http://marc.theaimsgroup.com/?l=linux-netdev&m=116102409931269&w=2)
d80211: remove initialization of unused xr structure members
(http://marc.theaimsgroup.com/?l=linux-netdev&m=116076811809305&w=4)
d80211: remove unused xr structure members, interface, etc.
(http://marc.theaimsgroup.com/?l=linux-netdev&m=115989929600617&w=4)
For key_conf_bitfields.patch change the new flags member to u8 from u32.
For tx_control_bitfields.patch move the rts_cts_duration and retry_limit members
in ieee80211_tx_control to allow for smaller structure size and change the
flags member from u32 to u16.
For tx_status_bitfields.patch, in
drivers/net/wireless/d80211/bcm43xx/bcm43xx_dma.c and
drivers/net/wireless/d80211/bcm43xx/bcm43xx_pio.c note that
ieee80211_tx_status is already zero'd, so the ack bit only needs to be
set, not cleared.
--
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [take3 0/5] d80211: remove bitfields from include/net/d80211.h
2006-10-25 18:42 [take3 0/5] d80211: remove bitfields from include/net/d80211.h David Kimdon
@ 2006-10-25 19:01 ` Jeff Garzik
2006-10-25 19:17 ` David Kimdon
0 siblings, 1 reply; 6+ messages in thread
From: Jeff Garzik @ 2006-10-25 19:01 UTC (permalink / raw)
To: David Kimdon; +Cc: netdev, John W. Linville, Jiri Benc
On Wed, Oct 25, 2006 at 11:42:44AM -0700, David Kimdon wrote:
> Continue d80211 bitfield removal. In general, compilers have
> difficulty generating efficient code for bitfields. This patchset
> removes all bitfields from include/net/d80211.h.
>
> I converted the 1 bit bitfields into a bit in a u32/u16 or u8 flags
> structure member. Larger bitfields I converted into their
> u8/u16/whatever equivalent.
For bit flags, usually it is best to use up to 32 bits of an
unsigned long, which guarantees that you use a machine integer for
all platforms.
Jeff
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [take3 0/5] d80211: remove bitfields from include/net/d80211.h
2006-10-25 19:01 ` Jeff Garzik
@ 2006-10-25 19:17 ` David Kimdon
2006-10-25 19:28 ` Jeff Garzik
0 siblings, 1 reply; 6+ messages in thread
From: David Kimdon @ 2006-10-25 19:17 UTC (permalink / raw)
To: Jeff Garzik; +Cc: David Kimdon, netdev, John W. Linville, Jiri Benc
On Wed, Oct 25, 2006 at 03:01:29PM -0400, Jeff Garzik wrote:
> On Wed, Oct 25, 2006 at 11:42:44AM -0700, David Kimdon wrote:
> > Continue d80211 bitfield removal. In general, compilers have
> > difficulty generating efficient code for bitfields. This patchset
> > removes all bitfields from include/net/d80211.h.
> >
> > I converted the 1 bit bitfields into a bit in a u32/u16 or u8 flags
> > structure member. Larger bitfields I converted into their
> > u8/u16/whatever equivalent.
>
> For bit flags, usually it is best to use up to 32 bits of an
> unsigned long, which guarantees that you use a machine integer for
> all platforms.
That is how I originally had the patch, but then had a question about
increasing structure size so I dropped flags to u16 or u8 for
structures that were made larger by the bitfield removal.
For the key_conf bitfields size doesn't matter much. For the tx_control
bitfields size matters a bit more since it is needed per-packets and
dirvers currently need to store a copy to pass to the tx complete
handler.
Thoughts?
David
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [take3 0/5] d80211: remove bitfields from include/net/d80211.h
2006-10-25 19:17 ` David Kimdon
@ 2006-10-25 19:28 ` Jeff Garzik
2006-11-03 3:30 ` John W. Linville
0 siblings, 1 reply; 6+ messages in thread
From: Jeff Garzik @ 2006-10-25 19:28 UTC (permalink / raw)
To: David Kimdon; +Cc: netdev, John W. Linville, Jiri Benc
On Wed, Oct 25, 2006 at 12:17:02PM -0700, David Kimdon wrote:
> That is how I originally had the patch, but then had a question about
> increasing structure size so I dropped flags to u16 or u8 for
> structures that were made larger by the bitfield removal.
On non-x86 platforms, u16 and u8 generate shitty code too. Not as
shitty as bitfields, but still shitty.
Jeff
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [take3 0/5] d80211: remove bitfields from include/net/d80211.h
2006-10-25 19:28 ` Jeff Garzik
@ 2006-11-03 3:30 ` John W. Linville
2006-11-08 15:39 ` David Kimdon
0 siblings, 1 reply; 6+ messages in thread
From: John W. Linville @ 2006-11-03 3:30 UTC (permalink / raw)
To: Jeff Garzik; +Cc: David Kimdon, netdev, Jiri Benc
On Wed, Oct 25, 2006 at 03:28:03PM -0400, Jeff Garzik wrote:
> On Wed, Oct 25, 2006 at 12:17:02PM -0700, David Kimdon wrote:
> > That is how I originally had the patch, but then had a question about
> > increasing structure size so I dropped flags to u16 or u8 for
> > structures that were made larger by the bitfield removal.
>
> On non-x86 platforms, u16 and u8 generate shitty code too. Not as
> shitty as bitfields, but still shitty.
David, may I presume there will be a "take4"?
John
--
John W. Linville
linville@tuxdriver.com
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2006-11-08 15:40 UTC | newest]
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2006-10-25 18:42 [take3 0/5] d80211: remove bitfields from include/net/d80211.h David Kimdon
2006-10-25 19:01 ` Jeff Garzik
2006-10-25 19:17 ` David Kimdon
2006-10-25 19:28 ` Jeff Garzik
2006-11-03 3:30 ` John W. Linville
2006-11-08 15:39 ` David Kimdon
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