Re: Git and GCC

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From: David Miller
Date: Friday, December 7, 2007 - 6:55 pm

From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Fri, 7 Dec 2007 09:23:47 -0800 (PST)


Unfortunately they are hypervisor calls, and you have to give
the thing physical addresses for the buffer to work on, so
letting userland get at it directly isn't currently doable.

I still believe that there are cases where userland can take
advantage of in-kernel crypto devices, such as when we are
streaming the data into the kernel anyways (for a write()
or sendmsg()) and the user just wants the transformation to
be done on that stream.

As a specific case, hardware crypto SSL support works quite
well for sendmsg() user packet data.  And this the kind of API
Solaris provides to get good SSL performance with Niagara.


Ok.


zlib is really hard to optimize on Sparc, I've tried numerous times.
Actually compress is the real cycle killer, and in that case the inner
loop wants to dereference 2-byte shorts at a time but they are
unaligned half of the time, and any the check for alignment nullifies
the gains of avoiding the two byte loads.

Uncompress I don't think is optimized at all on any platform with
asm stuff like the compress side is.  It's a pretty straightforward
transformation and the memory accesses dominate the overhead.

I'll do some profiling to see what might be worth looking into.
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Messages in current thread:
Re: Git and GCC, David Miller, (Wed Dec 5, 7:52 pm)
Re: Git and GCC, Daniel Berlin, (Wed Dec 5, 8:47 pm)
Re: Git and GCC, David Miller, (Wed Dec 5, 9:20 pm)
Re: Git and GCC, Harvey Harrison, (Wed Dec 5, 9:25 pm)
Re: Git and GCC, Harvey Harrison, (Wed Dec 5, 9:28 pm)
Re: Git and GCC, Daniel Berlin, (Wed Dec 5, 9:32 pm)
Re: Git and GCC, David Miller, (Wed Dec 5, 9:48 pm)
Re: Git and GCC, Linus Torvalds, (Wed Dec 5, 9:54 pm)
Re: Git and GCC, Harvey Harrison, (Wed Dec 5, 10:04 pm)
Re: Git and GCC, Daniel Berlin, (Wed Dec 5, 10:11 pm)
Re: Git and GCC, Harvey Harrison, (Wed Dec 5, 10:15 pm)
Re: Git and GCC, Daniel Berlin, (Wed Dec 5, 10:17 pm)
Re: Git and GCC, Linus Torvalds, (Wed Dec 5, 11:09 pm)
Re: Git and GCC, Jon Smirl, (Wed Dec 5, 11:47 pm)
Re: Git and GCC, Jeff King, (Thu Dec 6, 12:15 am)
Re: Git and GCC, Harvey Harrison, (Thu Dec 6, 12:49 am)
Re: Git and GCC, David Brown, (Thu Dec 6, 1:11 am)
Re: Git and GCC, Johannes Schindelin, (Thu Dec 6, 4:57 am)
[PATCH] gc --aggressive: make it really aggressive, Johannes Schindelin, (Thu Dec 6, 5:03 am)
Re: Git and GCC, Ismail , (Thu Dec 6, 5:04 am)
Re: [PATCH] gc --aggressive: make it really aggressive, Theodore Tso, (Thu Dec 6, 6:42 am)
Re: Git and GCC, Nicolas Pitre, (Thu Dec 6, 7:01 am)
Re: [PATCH] gc --aggressive: make it really aggressive, Nicolas Pitre, (Thu Dec 6, 7:15 am)
Re: Git and GCC, Nicolas Pitre, (Thu Dec 6, 7:18 am)
Re: [PATCH] gc --aggressive: make it really aggressive, Pierre Habouzit, (Thu Dec 6, 7:22 am)
Re: [PATCH] gc --aggressive: make it really aggressive, Harvey Harrison, (Thu Dec 6, 8:30 am)
Re: [PATCH] gc --aggressive: make it really aggressive, Johannes Schindelin, (Thu Dec 6, 8:55 am)
Re: [PATCH] gc --aggressive: make it really aggressive, Johannes Schindelin, (Thu Dec 6, 8:56 am)
Re: [PATCH] gc --aggressive: make it really aggressive, Linus Torvalds, (Thu Dec 6, 9:19 am)
Re: [PATCH] gc --aggressive: make it really aggressive, David Kastrup, (Thu Dec 6, 10:05 am)
Re: Git and GCC, Jeff King, (Thu Dec 6, 10:39 am)
Re: Git and GCC, Nicolas Pitre, (Thu Dec 6, 11:02 am)
Re: Git and GCC, Daniel Berlin, (Thu Dec 6, 11:04 am)
Re: Git and GCC, NightStrike, (Thu Dec 6, 11:24 am)
Re: Git and GCC, Linus Torvalds, (Thu Dec 6, 11:29 am)
Re: Git and GCC, Linus Torvalds, (Thu Dec 6, 11:35 am)
Re: Git and GCC, Linus Torvalds, (Thu Dec 6, 11:45 am)
Re: Git and GCC, Jon Smirl, (Thu Dec 6, 11:55 am)
Re: Git and GCC, Nicolas Pitre, (Thu Dec 6, 12:08 pm)
Re: Git and GCC, Jon Loeliger, (Thu Dec 6, 12:12 pm)
Re: Git and GCC, Linus Torvalds, (Thu Dec 6, 12:39 pm)
Re: Git and GCC, Junio C Hamano, (Thu Dec 6, 1:04 pm)
Re: Git and GCC, Junio C Hamano, (Thu Dec 6, 2:02 pm)
Re: Git and GCC, Jon Smirl, (Thu Dec 6, 2:39 pm)
Re: Git and GCC, Nicolas Pitre, (Thu Dec 6, 3:08 pm)
Re: Git and GCC, Jon Smirl, (Thu Dec 6, 3:11 pm)
Re: Git and GCC, Jon Smirl, (Thu Dec 6, 3:22 pm)
Re: Git and GCC, David Kastrup, (Thu Dec 6, 3:26 pm)
Re: Git and GCC, Nicolas Pitre, (Thu Dec 6, 3:30 pm)
[OT] Re: Git and GCC, Randy Dunlap, (Thu Dec 6, 3:38 pm)
Re: Git and GCC, Jon Smirl, (Thu Dec 6, 3:44 pm)
Re: Git and GCC, Jakub Narebski, (Thu Dec 6, 5:29 pm)
Re: Git and GCC, Harvey Harrison, (Thu Dec 6, 7:42 pm)
Re: Git and GCC, Linus Torvalds, (Thu Dec 6, 8:01 pm)
Re: Git and GCC, David Miller, (Thu Dec 6, 8:31 pm)
Re: Git and GCC, Jon Smirl, (Thu Dec 6, 9:06 pm)
Re: Git and GCC, Nicolas Pitre, (Thu Dec 6, 9:21 pm)
Re: Git and GCC, Linus Torvalds, (Thu Dec 6, 10:21 pm)
Re: Git and GCC, NightStrike, (Thu Dec 6, 10:36 pm)
Re: Git and GCC, Jeff King, (Thu Dec 6, 11:38 pm)
Re: Git and GCC, Jeff King, (Thu Dec 6, 11:50 pm)
Re: Git and GCC, Jon Smirl, (Fri Dec 7, 12:08 am)
Re: Git and GCC, Jon Smirl, (Fri Dec 7, 12:10 am)
Re: Git and GCC, Jeff King, (Fri Dec 7, 12:27 am)
Re: Git and GCC, Jeff King, (Fri Dec 7, 12:31 am)
Re: Git and GCC, David Miller, (Fri Dec 7, 5:53 am)
Re: Git and GCC, Linus Torvalds, (Fri Dec 7, 10:23 am)
Re: Git and GCC, Nicolas Pitre, (Fri Dec 7, 12:36 pm)
Re: Git and GCC, Giovanni Bajo, (Fri Dec 7, 1:26 pm)
Re: Git and GCC, Jakub Narebski, (Fri Dec 7, 3:14 pm)
Re: Git and GCC, Luke Lu, (Fri Dec 7, 4:04 pm)
Re: Git and GCC, Giovanni Bajo, (Fri Dec 7, 4:14 pm)
Re: Git and GCC, Daniel Berlin, (Fri Dec 7, 4:33 pm)
Re: Git and GCC, Harvey Harrison, (Fri Dec 7, 5:47 pm)
Re: Git and GCC, David Miller, (Fri Dec 7, 6:55 pm)
Re: Git and GCC, Johannes Schindelin, (Sat Dec 8, 5:00 am)
Re: Git and GCC, Gabriel Paubert, (Mon Dec 10, 2:54 am)
Re: Git and GCC, David Miller, (Mon Dec 10, 2:57 am)
Re: Git and GCC, Nicolas Pitre, (Mon Dec 10, 8:35 am)
Re: [PATCH] gc --aggressive: make it really aggressive, Johannes Schindelin, (Wed Mar 18, 9:01 am)
Re: [PATCH] gc --aggressive: make it really aggressive, Teemu Likonen, (Wed Mar 18, 9:27 am)
Re: [PATCH] gc --aggressive: make it really aggressive, Nicolas Pitre, (Wed Mar 18, 11:02 am)