Date: Sat, 26 Oct 2019 08:24:09 +0200 From: Antoine Brodin <antoine@freebsd.org> To: Konstantin Belousov <kib@freebsd.org> Cc: src-committers <src-committers@freebsd.org>, svn-src-all@freebsd.org, svn-src-head@freebsd.org, Gerald Pfeifer <gerald@freebsd.org> Subject: Re: svn commit: r354095 - in head/sys: amd64/amd64 amd64/include kern Message-ID: <CAALwa8n9WK8FGn%2BmB=FoNuf=%2B8JmOtpg00m=KB3Z_O4Y38PMAw@mail.gmail.com> In-Reply-To: <201910252009.x9PK9gIV092660@repo.freebsd.org> References: <201910252009.x9PK9gIV092660@repo.freebsd.org>
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On Fri, Oct 25, 2019 at 10:09 PM Konstantin Belousov <kib@freebsd.org> wrote: > > Author: kib > Date: Fri Oct 25 20:09:42 2019 > New Revision: 354095 > URL: https://svnweb.freebsd.org/changeset/base/354095 > > Log: > amd64: move pcb out of kstack to struct thread. > > This saves 320 bytes of the precious stack space. > > The only negative aspect of the change I can think of is that the > struct thread increased by 320 bytes obviously, and that 320 bytes are > not swapped out anymore. I believe the freed stack space is much more > important than that. Also, current struct thread size is 1392 bytes > on amd64, so UMA will allocate two thread structures per (4KB) slab, > which leaves a space for pcb without increasing zone memory use. > > Reviewed by: alc, markj > Tested by: pho > Sponsored by: The FreeBSD Foundation > MFC after: 2 weeks > Differential revision: https://reviews.freebsd.org/D22138 Hi, It seems that this breaks at least some versions of gcc: In file included from /usr/include/sys/proc.h:75, from /usr/include/sys/user.h:51, from ./md-unwind-support.h:34, from /wrkdirs/usr/ports/lang/gcc10-devel/work/gcc-10-20191020/libgcc/unwind-dw2.c:412: /usr/include/machine/proc.h:76:13: error: field 'md_pcb' has incomplete type 76 | struct pcb md_pcb; | ^~~~~~ Antoine
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