From: Matthew Wilcox <willy@infradead.org>
To: Jan Kara <jack@suse.cz>
Cc: Seema Pandit <seema.pandit@intel.com>,
linux-nvdimm <linux-nvdimm@lists.01.org>,
Boaz Harrosh <openosd@gmail.com>,
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>
Subject: Re: [PATCH] dax: Fix missed PMD wakeups
Date: Thu, 11 Jul 2019 07:13:50 -0700 [thread overview]
Message-ID: <20190711141350.GS32320@bombadil.infradead.org> (raw)
In-Reply-To: <20190710202647.GA7269@quack2.suse.cz>
On Wed, Jul 10, 2019 at 10:26:47PM +0200, Jan Kara wrote:
> On Wed 10-07-19 13:15:39, Matthew Wilcox wrote:
> > On Wed, Jul 10, 2019 at 09:02:04PM +0200, Jan Kara wrote:
> > > +#define DAX_ENTRY_CONFLICT dax_make_entry(pfn_to_pfn_t(1), DAX_EMPTY)
> >
> > I was hoping to get rid of DAX_EMPTY ... it's almost unused now. Once
> > we switch to having a single DAX_LOCK value instead of a single bit,
> > I think it can go away, freeing up two bits.
> >
> > If you really want a special DAX_ENTRY_CONFLICT, I think we can make
> > one in the 2..4094 range.
> >
> > That aside, this looks pretty similar to the previous patch I sent, so
> > if you're now happy with this, let's add
> >
> > #define XA_DAX_CONFLICT_ENTRY xa_mk_internal(258)
> >
> > to xarray.h and do it that way?
>
> Yeah, that would work for me as well. The chosen value for DAX_ENTRY_CONFLICT
> was pretty arbitrary. Or we could possibly use:
>
> #define DAX_ENTRY_CONFLICT XA_ZERO_ENTRY
>
> so that we don't leak DAX-specific internal definition into xarray.h?
I don't want to use the ZERO entry as our conflict marker because that
could legitimately appear in an XArray. Not the i_pages XArray today,
but I hold out hope for using that in place of the DAX_ZERO_PAGE bit too.
That's going to be a bit more tricky since we currently distinguish
between DAX_ZERO_PAGE and DAX_ZERO_PAGE | DAX_PMD.
However, the XA_RETRY_ENTRY might be a good choice. It doesn't normally
appear in an XArray (it may appear if you're looking at a deleted node,
but since we're holding the lock, we can't see deleted nodes).
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WARNING: multiple messages have this Message-ID (diff)
From: Matthew Wilcox <willy@infradead.org>
To: Jan Kara <jack@suse.cz>
Cc: Dan Williams <dan.j.williams@intel.com>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Boaz Harrosh <openosd@gmail.com>, stable <stable@vger.kernel.org>,
Robert Barror <robert.barror@intel.com>,
Seema Pandit <seema.pandit@intel.com>,
linux-nvdimm <linux-nvdimm@lists.01.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] dax: Fix missed PMD wakeups
Date: Thu, 11 Jul 2019 07:13:50 -0700 [thread overview]
Message-ID: <20190711141350.GS32320@bombadil.infradead.org> (raw)
In-Reply-To: <20190710202647.GA7269@quack2.suse.cz>
On Wed, Jul 10, 2019 at 10:26:47PM +0200, Jan Kara wrote:
> On Wed 10-07-19 13:15:39, Matthew Wilcox wrote:
> > On Wed, Jul 10, 2019 at 09:02:04PM +0200, Jan Kara wrote:
> > > +#define DAX_ENTRY_CONFLICT dax_make_entry(pfn_to_pfn_t(1), DAX_EMPTY)
> >
> > I was hoping to get rid of DAX_EMPTY ... it's almost unused now. Once
> > we switch to having a single DAX_LOCK value instead of a single bit,
> > I think it can go away, freeing up two bits.
> >
> > If you really want a special DAX_ENTRY_CONFLICT, I think we can make
> > one in the 2..4094 range.
> >
> > That aside, this looks pretty similar to the previous patch I sent, so
> > if you're now happy with this, let's add
> >
> > #define XA_DAX_CONFLICT_ENTRY xa_mk_internal(258)
> >
> > to xarray.h and do it that way?
>
> Yeah, that would work for me as well. The chosen value for DAX_ENTRY_CONFLICT
> was pretty arbitrary. Or we could possibly use:
>
> #define DAX_ENTRY_CONFLICT XA_ZERO_ENTRY
>
> so that we don't leak DAX-specific internal definition into xarray.h?
I don't want to use the ZERO entry as our conflict marker because that
could legitimately appear in an XArray. Not the i_pages XArray today,
but I hold out hope for using that in place of the DAX_ZERO_PAGE bit too.
That's going to be a bit more tricky since we currently distinguish
between DAX_ZERO_PAGE and DAX_ZERO_PAGE | DAX_PMD.
However, the XA_RETRY_ENTRY might be a good choice. It doesn't normally
appear in an XArray (it may appear if you're looking at a deleted node,
but since we're holding the lock, we can't see deleted nodes).
next prev parent reply other threads:[~2019-07-11 14:16 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-03 7:24 [PATCH] dax: Fix missed PMD wakeups Dan Williams
2019-07-03 7:24 ` Dan Williams
2019-07-03 12:17 ` Matthew Wilcox
2019-07-03 12:17 ` Matthew Wilcox
2019-07-03 17:01 ` Dan Williams
2019-07-03 17:01 ` Dan Williams
2019-07-03 19:53 ` Matthew Wilcox
2019-07-03 19:53 ` Matthew Wilcox
2019-07-03 21:28 ` Dan Williams
2019-07-03 21:28 ` Dan Williams
2019-07-04 3:27 ` Matthew Wilcox
2019-07-04 3:27 ` Matthew Wilcox
2019-07-04 13:00 ` Boaz Harrosh
2019-07-04 13:00 ` Boaz Harrosh
2019-07-04 13:58 ` Matthew Wilcox
2019-07-04 13:58 ` Matthew Wilcox
2019-07-04 14:32 ` Boaz Harrosh
2019-07-04 14:32 ` Boaz Harrosh
2019-07-04 16:54 ` Jan Kara
2019-07-04 16:54 ` Jan Kara
2019-07-04 19:14 ` Matthew Wilcox
2019-07-04 19:14 ` Matthew Wilcox
2019-07-04 23:27 ` Dan Williams
2019-07-04 23:27 ` Dan Williams
2019-07-05 19:10 ` Matthew Wilcox
2019-07-05 19:10 ` Matthew Wilcox
2019-07-05 20:47 ` Dan Williams
2019-07-05 20:47 ` Dan Williams
2019-07-10 19:02 ` Jan Kara
2019-07-10 19:02 ` Jan Kara
2019-07-10 20:15 ` Matthew Wilcox
2019-07-10 20:15 ` Matthew Wilcox
2019-07-10 20:26 ` Jan Kara
2019-07-10 20:26 ` Jan Kara
2019-07-11 14:13 ` Matthew Wilcox [this message]
2019-07-11 14:13 ` Matthew Wilcox
2019-07-11 15:25 ` Matthew Wilcox
2019-07-11 15:25 ` Matthew Wilcox
2019-07-11 15:41 ` Jan Kara
2019-07-11 15:41 ` Jan Kara
2019-07-17 3:39 ` Dan Williams
2019-07-17 3:39 ` Dan Williams
2019-07-29 12:02 ` Jan Kara
2019-07-29 12:02 ` Jan Kara
2019-07-29 15:18 ` Dan Williams
2019-07-29 15:18 ` Dan Williams
2019-07-11 3:08 ` Matthew Wilcox
2019-07-11 3:08 ` Matthew Wilcox
2019-07-11 7:48 ` Jan Kara
2019-07-11 7:48 ` Jan Kara
2019-07-11 13:28 ` Matthew Wilcox
2019-07-11 13:28 ` Matthew Wilcox
2019-07-11 3:35 ` Matthew Wilcox
2019-07-11 3:35 ` Matthew Wilcox
2019-07-11 8:06 ` Jan Kara
2019-07-11 8:06 ` Jan Kara
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