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Date: Sun, 3 Nov 2019 14:01:41 -0500 From: "Theodore Y. Ts'o" <tytso@....edu> To: Jan Kara <jack@...e.cz> Cc: linux-ext4@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>, Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...nel.org>, Steven Rostedt <rostedt@...dmis.org>, Anna-Maria Gleixner <anna-maria@...utronix.de>, Julia Cartwright <julia@...com> Subject: Re: [PATCH 0/7 v2] jbd2: Bit spinlock conversions On Fri, Aug 09, 2019 at 02:42:26PM +0200, Jan Kara wrote: > Hello, > > This series is derived from Thomas' series to get rid of bit spinlocks in > buffer head code. These patches convert BH_State bit spinlock to an ordinary > spinlock inside struct journal_head and somewhat reduce the critical section > under BH_JournalHead bit spinlock so that it is fine for RT. > > Motivation from original Thomas' series: > > Bit spinlocks are problematic if PREEMPT_RT is enabled. They disable > preemption, which is undesired for latency reasons and breaks when regular > spinlocks are taken within the bit_spinlock locked region because regular > spinlocks are converted to 'sleeping spinlocks' on RT. > > Bit spinlocks are also not covered by lock debugging, e.g. lockdep. With > the spinlock substitution in place, they can be exposed via a new config > switch: CONFIG_DEBUG_BIT_SPINLOCKS. > > Ted, can you pick up these patches? Thanks! I've landed this patch set on the ext4 git tree. Thanks! - Ted
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