Date: Sun, 5 Feb 2017 13:03:08 +0300 From: Slawa Olhovchenkov <slw@zxy.spb.ru> To: Mateusz Guzik <mjguzik@gmail.com> Cc: Mateusz Guzik <mjg@FreeBSD.org>, src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r313275 - in head/sys: kern sys Message-ID: <20170205100308.GF6599@zxy.spb.ru> In-Reply-To: <20170205100127.GC4375@dft-labs.eu> References: <201702050804.v1584Cim052478@repo.freebsd.org> <20170205100010.GB5366@zxy.spb.ru> <20170205100127.GC4375@dft-labs.eu>
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On Sun, Feb 05, 2017 at 11:01:28AM +0100, Mateusz Guzik wrote: > On Sun, Feb 05, 2017 at 01:00:11PM +0300, Slawa Olhovchenkov wrote: > > On Sun, Feb 05, 2017 at 08:04:12AM +0000, Mateusz Guzik wrote: > > > > > Author: mjg > > > Date: Sun Feb 5 08:04:11 2017 > > > New Revision: 313275 > > > URL: https://svnweb.freebsd.org/changeset/base/313275 > > > > > > Log: > > > mtx: move lockstat handling out of inline primitives > > > > > > Lockstat requires checking if it is enabled and if so, calling a 6 argument > > > function. Further, determining whether to call it on unlock requires > > > pre-reading the lock value. > > > > > > This is problematic in at least 3 ways: > > > - more branches in the hot path than necessary > > > - additional cacheline ping pong under contention > > > - bigger code > > > > > > Instead, check first if lockstat handling is necessary and if so, just fall > > > back to regular locking routines. For this purpose a new macro is introduced > > > (LOCKSTAT_PROFILE_ENABLED). > > > > > > LOCK_PROFILING uninlines all primitives. Fold in the current inline lock > > > variant into the _mtx_lock_flags to retain the support. With this change > > > the inline variants are not used when LOCK_PROFILING is defined and thus > > > can ignore its existence. > > > > > > This results in: > > > text data bss dec hex filename > > > 22259667 1303208 4994976 28557851 1b3c21b kernel.orig > > > 21797315 1303208 4994976 28095499 1acb40b kernel.patched > > > > > > i.e. about 3% reduction in text size. > > > > > > A remaining action is to remove spurious arguments for internal kernel > > > consumers. > > > > Do you planed MFC all of this? > > Yes, around march. Thanks!
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