Re: [PATCH] dax: Fix missed PMD wakeups

From: Boaz Harrosh <openosd@gmail.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: Jan Kara <jack@suse.cz>, linux-nvdimm <linux-nvdimm@lists.01.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	stable <stable@vger.kernel.org>,
	Robert Barror <robert.barror@intel.com>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	Seema Pandit <seema.pandit@intel.com>
Subject: Re: [PATCH] dax: Fix missed PMD wakeups
Date: Thu, 4 Jul 2019 17:32:23 +0300	[thread overview]
Message-ID: <bfe7c33d-7c3c-dcc0-5408-e23ea8223ef0@gmail.com> (raw)
In-Reply-To: <20190704135804.GL1729@bombadil.infradead.org>

On 04/07/2019 16:58, Matthew Wilcox wrote:
> On Thu, Jul 04, 2019 at 04:00:00PM +0300, Boaz Harrosh wrote:
<>
>> Matthew you must be kidding an ilog2 in binary is zero clocks
>> (Return the highest bit or something like that)
> 
> You might want to actually check the documentation instead of just
> making shit up.
> 

Yes you are right I stand corrected. Must be smoking ;-)

> https://www.agner.org/optimize/instruction_tables.pdf
> 
> I think in this instance what we want is BSR (aka ffz) since the input is
> going to be one of 0, 1, 3, 7, 15 or 31 (and we want 0, 1, 2, 3, 4, 5 as
> results).
> 
<>
> The compiler doesn't know the range of 'sibs'.  Unless we do the
> profile-feedback thing.
> 

Would you please consider the use of get_order() macro from #include <getorder.h>
Just for the sake of understanding? (Or at least a comment)

Thanks
Boaz
_______________________________________________
Linux-nvdimm mailing list
Linux-nvdimm@lists.01.org
https://lists.01.org/mailman/listinfo/linux-nvdimm