On Wed, Oct 8, 2008 at 10:02 AM, Johannes Berg <johannes@xxxxxxxxxxxxxxxx> wrote: > On Tue, 2008-10-07 at 22:46 +0200, Tomas Winkler wrote: >> >> > bytes (with nibbles): | . | . | . | . | . | . || . | . | . | . | . | . | >> >> > | addr 1 |len1 || addr 2 |len2 | >> >> > your forced layout: | | | | >> >> > my layout: | | || | | >> >> > >> >> > Note how this actually matches the border between the border between the >> >> > two descriptors, the || border. >> >> >> >> Your layout put addr2 (which is 32 bit) sits on 16 bit boundary >> > >> > So? Yours makes it need two words, which is even less efficient to >> > access. And since the struct is packed, on those architectures that >> > don't do unaligned accesses efficiently won't need any put_unaligned >> > either. >> > >> > Also, keep in mind that address 2 is _never_ used at all anyway > >> This is not correct we always use first 2 pointers. First for tx command >> second for the actual packet. > > Ok so you use two. My only point is just to make sure that you understand that __never__ is not correct Writing three words in total. I strongly suggest that > you have WAY more trouble in iwlwifi than an imagined performance issue > coming from a corrected and understandable struct layout. You are rally trying breaking into open doors Currently I'm more concern with correctness then performance so I wanted to rise hopefully all issues. I'm testing your layout it's work so far in my home setup. I'm on holidays till EOW so I will be able to give it some more stress in Lab only next week. > >> > because >> > we don't and cannot do fragmented frames due to the lack of IP >> > checksumming in hardware, as I and davem have tried to explain to you >> > multiple times already. >> >> This is bad side of current Linux implementation > > Look, we've tried to explain it to you so many times that it simply is > not possible to enable fragment collection without IP checksumming in > hardware that I don't know what to tell you. This may sound offensive, > but are you really too stupid to understand it? Okay not fair from my side I just couldn't resist ... I just really like the subject :) Tomas -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
