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Date:   Fri, 18 May 2018 11:51:02 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Kent Overstreet <kent.overstreet@gmail.com>
Cc:     linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        Andrew Morton <akpm@linux-foundation.org>,
        Dave Chinner <dchinner@redhat.com>, darrick.wong@oracle.com,
        tytso@mit.edu, linux-btrfs@vger.kernel.org, clm@fb.com,
        jbacik@fb.com, viro@zeniv.linux.org.uk, willy@infradead.org
Subject: Re: [PATCH 03/10] locking: bring back lglocks
Message-ID: <20180518095102.GE12217@hirez.programming.kicks-ass.net>
References: <20180518074918.13816-1-kent.overstreet@gmail.com>
 <20180518074918.13816-7-kent.overstreet@gmail.com>
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On Fri, May 18, 2018 at 03:49:04AM -0400, Kent Overstreet wrote:
> bcachefs makes use of them - also, add a proper lg_lock_init()

Why?! lglocks are horrid things, we got rid of them for a reason. They
have terrifying worst case preemption off latencies.

Why can't you use something like per-cpu rwsems?