David Miller a écrit :
From: Eric Dumazet <[EMAIL PROTECTED]>
Date: Wed, 18 Oct 2006 07:08:07 +0200
Each route entry includes a 'struct flow'. This structure has a
current size of 80 bytes. This patch makes a size reduction
depending on
CONFIG_IPV6/CONFIG_IPV6_MODULE/CONFIG_DECNET/CONFIG_IP_ROUTE_FWMARK
For a platform doing IPV4 only, the new size is 36 bytes (instead of
80) As many routers are base on PIII (L1_CACHE_SIZE=32), this saves
one cache line per rtable entry.
I don't like these kinds of patches because %99 of people will never
ever realize the "savings" because distribution vendors will always,
unlaterally, enable everything.
For example, I'm still pending to cut the patch that kills the "struct
flow" from inet_sock's cork area since it really isn't needed.
I'd rather do things that get rid of the size in a way that benefits
everyone, regardless of kernel config. I also would totally support
a patch that got rid of all the config ifdefs used in struct sk_buff.
I agree with you David (I dont like these patches as well), but I know a lot
of sysadmins who recompile themselves their kernels because they have old
machines and/or want optimized kernels, not 'big bloated kernels' from distro
guys running the very latest intel/amd bomb.
As long the #ifdefs are in .h files, I do think the pain is small.
Fact is linux has many CONFIG_XXXX things, and as many possible binary
versions for a single linux-2.6.XX version as atoms in the universe... A
distro cannot provides all version and just provide the largest possible one,
containing many obsolete/funny features.
How many people are using DECNET and want to pay the price of this 20 bytes
dnports structure ?
Eric
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