Re: bin/50638: Extreme slowness on loading gzipped kernels on oldCPUs

[Joerg Sonnenberger <joerg%britannica.bec.de@localhost>]

The following reply was made to PR bin/50638; it has been noted by GNATS.

From: Joerg Sonnenberger <joerg%britannica.bec.de@localhost>
To: Izumi Tsutsui <tsutsui%ceres.dti.ne.jp@localhost>
Cc: gnats-bugs%NetBSD.org@localhost
Subject: Re: bin/50638: Extreme slowness on loading gzipped kernels on oldCPUs
Date: Mon, 11 Jan 2016 17:50:08 +0100

 On Tue, Jan 12, 2016 at 01:27:52AM +0900, Izumi Tsutsui wrote:
 > joerg@ wrote:
 > 
 > > >  If someone complains slowness on x86, others might look at it.
 > > >  That's all.
 > > 
 > > It is not noticable on semi-modern hardware. Even the slow version takes
 > > less than 1s, IO is still worse.
 > 
 > Then there is no reason to try a possibly faster version
 > which will do nothing on loading kernels anyway.
 > I will add an option to simply disable CRC calculation in
 > the libsa cread() function to solve the main issue of this PR.
 > 
 > You can still suggest kernel crypto guys to replace current zlib based
 > crc32() function in libkern with your libarchive one in another PR.
 
 You asked about possible options. You missed a valid one. Now you don't
 want to hear that your preferred choice may not be the best approach.
 Seriously, why bother asking in first place?
 
 > 
 > > >  For example, persons who added crc32() into libkern didn't
 > > >  change the function name but did change an argument type,
 > > >  then it caused a conflict against the original zlib one.
 > > >  I cannot simply use zlib/crc32.c and I have to copy code
 > > >  from zlib/crc32.c to slightly modified libkern/crc32.c.
 > > 
 > > I mentioned the code specifically because it is much easier to use than
 > > the copy & pasting from zlib's dynamic table compution, which is might
 > > be somewhat faster for larger input, but also is larger in terms of code
 > > size. If you had looked, it would be have been quite clear.
 > 
 > I wish someone who has enough spare time will try it.
 
 The emails from you have already wasted way more time than copying the
 function and measuring is ever going to do.
 
 Joerg