lkml.org 
[lkml]   [2018]   [Feb]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [PATCH v2] libnvdimm: re-enable deep flush for pmem devices
Date
Dan Williams <dan.j.williams@intel.com> writes:

> On Mon, Feb 12, 2018 at 2:53 PM, Jeff Moyer <jmoyer@redhat.com> wrote:
>> Dave Jiang <dave.jiang@intel.com> writes:
>>
>>> Re-enable deep flush so that users always have a way to be sure that a write
>>> does make it all the way out to the NVDIMM. The PMEM driver writes always
>>> make it "all the way to the NVDIMM", and it relies on the ADR mechanism to
>>> flush the write buffers on power failure. Deep flush is there to explicitly
>>> flush those write buffers to protect against (rare) ADR failure.
>>> This change prevents a regression in deep flush behavior so that applications
>>> can continue to depend on fsync() as a mechanism to trigger deep flush in the
>>> filesystem-dax case.
>>
>> That's still very confusing text. Specifically, the part where you say
>> that pmem driver writes always make it to the DIMM. I think the
>> changelog could start with "Deep flush is there to explicitly flush
>> write buffers...." Anyway, the fix looks right to me.
>
> I ended up changing the commit message to this, let me know if it reads better:

Thanks. It's still unclear to me what the text, "The PMEM driver writes
always arrive at the NVDIMM" means. However, it's good enough.

Thanks!
Jeff

>
> libnvdimm: re-enable deep flush for pmem devices via fsync()
>
> Re-enable deep flush so that users always have a way to be sure that a
> write makes it all the way out to media. The PMEM driver writes always
> arrive at the NVDIMM, and it relies on the ADR (Asynchronous DRAM
> Refresh) mechanism to flush the write buffers on power failure. Deep
> flush is there to explicitly flush those write buffers to protect
> against (rare) ADR failure. This change prevents a regression in deep
> flush behavior so that applications can continue to depend on fsync() as
> a mechanism to trigger deep flush in the filesystem-DAX case.
>
> Fixes: 06e8ccdab15f4 ("acpi: nfit: Add support for detect platform
> CPU cache...")
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>

\
 
 \ /
  Last update: 2018-02-13 14:17    [W:0.045 / U:4.180 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site