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Date: Sun, 5 Feb 2017 13:00:11 +0300
From: Slawa Olhovchenkov <slw@zxy.spb.ru>
To: Mateusz Guzik <mjg@FreeBSD.org>
Cc: src-committers@freebsd.org, svn-src-all@freebsd.org,
 svn-src-head@freebsd.org
Subject: Re: svn commit: r313275 - in head/sys: kern sys
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References: <201702050804.v1584Cim052478@repo.freebsd.org>
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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?