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Date:      Wed, 27 Mar 2013 21:23:32 -0700
From:      Adrian Chadd <adrian@freebsd.org>
To:        Warner Losh <imp@bsdimp.com>
Cc:        freebsd-embedded@freebsd.org, Ian Lepore <ian@freebsd.org>
Subject:   Re: FreeBSD on the AP121 (AR9330)
Message-ID:  <CAJ-VmonR9UeNX=rybAgp0WmsRw-dRKtXoS2DSy2hUC6dA6vsqw@mail.gmail.com>
In-Reply-To: <B649B0AC-21B7-4C12-8114-E363134E8198@bsdimp.com>
References:  <CAJ-Vmom8sbMJvFn1ucGBSiptWtKPC0kE1Ss22Kj-WGVSkP_8ag@mail.gmail.com> <1364404612.36972.59.camel@revolution.hippie.lan> <CAJ-VmokJ40LDF4WeuAENkZR89iStEmnTGkojeA6brSRkSKgJ1w@mail.gmail.com> <65064C0E-1C1F-4C07-9CFB-DEEC1638A78D@bsdimp.com> <CAJ-VmokXmycjeBv=3qOyiwdq4hqQ9ubwuxCEFpA_UPKtQ%2BAYFQ@mail.gmail.com> <CAJ-Vmo=HFgWfd0HRNfcXRVPL6X-_gbg4Hs1Fbnj5TAGa-j6GNQ@mail.gmail.com> <CAJ-VmokKnWLYUvUkxf-H_drMMw4P0VqenZU2GXLkHKLyFne-fg@mail.gmail.com> <B649B0AC-21B7-4C12-8114-E363134E8198@bsdimp.com>

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On 27 March 2013 20:22, Warner Losh <imp@bsdimp.com> wrote:

> I was able to save about 40k by uninlining mutexes, etc. But that took th=
e AP96 kernel from 6.5MB to 6.4MB.

The AP96 is an all-in-one kernel for a much more useful system. The
AP91 is the kicker. Same architecture, but I have to shrink the kernel
down to fit inside an 896k lzma'ed partition. That, and 16MB of RAM
makes it very, very tight.

> 4680311  266388 1576752 6523451  638a3b /dune/imp/obj/mips.mips/dune/imp/=
FreeBSD/sys/AP96/kernel
> 4641469  266372 1576624 6484465  62f1f1 /dune/imp/obj/mips.mips/dune/imp/=
FreeBSD/sys/AP96/kernel

Ok, I'll try that. I wonder how badly it's going to affect performance
though. :-(

> Here's the top 10 in terms of text size:
>
>   57344     160   49184  106688   1a0c0 /dune/imp/obj/mips.mips/dune/imp/=
FreeBSD/sys/AP96/kern_umtx.o

This is likely due to the default size of the mtx array. I dropped
that from 512 to 64, no appreciable drop. :-(

>   57004     848      64   57916    e23c /dune/imp/obj/mips.mips/dune/imp/=
FreeBSD/sys/AP96/pci.o
>   48956   10672      80   59708    e93c /dune/imp/obj/mips.mips/dune/imp/=
FreeBSD/sys/AP96/scsi_all.o
>   48664    1680     256   50600    c5a8 /dune/imp/obj/mips.mips/dune/imp/=
FreeBSD/sys/AP96/vfs_subr.o
>   45156     624       0   45780    b2d4 /dune/imp/obj/mips.mips/dune/imp/=
FreeBSD/sys/AP96/if_ath.o
>   44932    2000     320   47252    b894 /dune/imp/obj/mips.mips/dune/imp/=
FreeBSD/sys/AP96/vfs_bio.o
>   41796     992     192   42980    a7e4 /dune/imp/obj/mips.mips/dune/imp/=
FreeBSD/sys/AP96/ffs_alloc.o
>   41376       0       0   41376    a1a0 /dune/imp/obj/mips.mips/dune/imp/=
FreeBSD/sys/AP96/if_ath_tx.o
>   38272    5120      80   43472    a9d0 /dune/imp/obj/mips.mips/dune/imp/=
FreeBSD/sys/AP96/kern_jail.o
>   34340     752     192   35284    89d4 /dune/imp/obj/mips.mips/dune/imp/=
FreeBSD/sys/AP96/cam_xpt.o
>
> two of which you might be able to do something about. One suspects that P=
CIe support could be compiled out of pci.o, and there's two from CAM, and a=
nother three from file systems... Maybe there's a smaller subset of CAM tha=
t can be compiled in for the USB drive support?

The AR724x uses PCIe; so I can't kill that.

CAM is a big one, unfortunately. It'd be nice if we had a smaller
layer for this but it seems a losing battle without the USB/CAM people
jumping in and considering it as part of their architecture.

> Last time I fought this battle, it was a battle of attrition: 20k here, 2=
0k there, 5k over there. Sadly, you'll need about 100 of these.  Also, inli=
ning can cause significant bloat, and we inline a lot...

The big big thing is how big some of the subsystems are. ~ 200k just
for FFS. ~100k just for uipc routines. mtx is 100k all up and that's
kind of scary. etc.

It'd be nice if we could trim that much code out of different
subsystems. I'm going to make a concerted effort to shrink down bits
of the wireless stack and ath driver as they're a bit too kitchen sink
for me. But I first need to fit a normal kernel in the damned thing.

Sniffle. :-( I really could do with some more help here.


Adrian



Adrian



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