From: Jan Kara <jack@suse.cz>
To: "Theodore Y. Ts'o" <tytso@mit.edu>
Cc: Jan Kara <jack@suse.cz>,
Sebastian Siewior <bigeasy@linutronix.de>,
Thomas Gleixner <tglx@linutronix.de>,
Matthew Wilcox <willy@infradead.org>,
LKML <linux-kernel@vger.kernel.org>,
linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>,
Anna-Maria Gleixner <anna-maria@linutronix.de>,
Steven Rostedt <rostedt@goodmis.org>,
Julia Cartwright <julia@ni.com>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Jan Kara <jack@suse.com>, Mark Fasheh <mark@fasheh.com>,
Joseph Qi <joseph.qi@linux.alibaba.com>,
Christoph Hellwig <hch@infradead.org>,
Joel Becker <jlbec@evilplan.org>
Subject: Re: [PATCH] fs/buffer: Make BH_Uptodate_Lock bit_spin_lock a regular spinlock_t
Date: Mon, 18 Nov 2019 10:35:44 +0100 [thread overview]
Message-ID: <20191118093544.GA17319@quack2.suse.cz> (raw)
In-Reply-To: <20191115173634.GC23689@mit.edu>
On Fri 15-11-19 12:36:34, Theodore Y. Ts'o wrote:
> On Fri, Nov 15, 2019 at 03:56:38PM +0100, Jan Kara wrote:
> > With some effort, we could even shrink struct buffer_head from 104 bytes
> > (on x86_64) to 96 bytes but I don't think that effort is worth it (I'd find
> > it better use of time to actually work on getting rid of buffer heads
> > completely).
>
> Is that really realistic? All aside from the very large number of
> file systems which use buffer_heads that would have to be reworked,
> the concept of buffer heads is pretty fundamental to how jbd2 is
> architected.
I think it is reasonably possible to remove buffer_heads from data path
(including direct IO path) of all filesystems. That way memory consumption
of buffer_heads becomes mostly irrelevant and we can have a look how much
from the current bh framework still makes sense...
Honza
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
next prev parent reply other threads:[~2019-11-18 11:58 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-20 17:08 [PATCH] fs/buffer: Make BH_Uptodate_Lock bit_spin_lock a regular spinlock_t Sebastian Siewior
2019-08-20 17:17 ` Matthew Wilcox
2019-08-20 18:01 ` Thomas Gleixner
2019-10-11 11:25 ` Sebastian Siewior
2019-11-15 14:56 ` Jan Kara
2019-11-15 17:36 ` Theodore Y. Ts'o
2019-11-18 9:35 ` Jan Kara [this message]
2019-11-15 17:54 ` [PATCH v2] " Sebastian Siewior
2019-11-18 9:38 ` Jan Kara
2019-11-18 13:28 ` [PATCH v3] " Sebastian Siewior
2019-11-19 9:30 ` Jan Kara
2019-11-19 10:00 ` Sebastian Siewior
2019-11-19 11:59 ` Jan Kara
2020-03-28 12:26 ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
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