Linux-NVDIMM Archive on lore.kernel.org
 help / color / Atom feed
From: Jeff Moyer <jmoyer@redhat.com>
To: Dan Williams <dan.j.williams@intel.com>
Cc: linux-nvdimm@lists.01.org,
	"Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
	linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH v2 4/4] libnvdimm/region: Introduce an 'align' attribute
Date: Fri, 14 Feb 2020 15:19:07 -0500
Message-ID: <x495zg8exc4.fsf@segfault.boston.devel.redhat.com> (raw)
In-Reply-To: <158155491952.3343782.4541070487858304628.stgit@dwillia2-desk3.amr.corp.intel.com> (Dan Williams's message of "Wed, 12 Feb 2020 16:48:39 -0800")

Dan Williams <dan.j.williams@intel.com> writes:

> The align attribute applies an alignment constraint for namespace
> creation in a region. Whereas the 'align' attribute of a namespace
> applied alignment padding via an info block, the 'align' attribute
> applies alignment constraints to the free space allocation.
>
> The default for 'align' is the maximum known memremap_compat_align()
> across all archs (16MiB from PowerPC at time of writing) multiplied by
> the number of interleave ways if there is blk-aliasing. The minimum is
> PAGE_SIZE and allows for the creation of cross-arch incompatible
> namespaces, just as previous kernels allowed, but the expectation is
> cross-arch and mode-independent compatibility by default.
>
> The regression risk with this change is limited to cases that were
> dependent on the ability to create unaligned namespaces, *and* for some
> reason are unable to opt-out of aligned namespaces by writing to
> 'regionX/align'. If such a scenario arises the default can be flipped
> from opt-out to opt-in of compat-aligned namespace creation, but that is
> a last resort. The kernel will otherwise continue to support existing
> defined misaligned namespaces.
>
> Unfortunately this change needs to touch several parts of the
> implementation at once:
>
> - region/available_size: expand busy extents to current align
> - region/max_available_extent: expand busy extents to current align
> - namespace/size: trim free space to current align
>
> ...to keep the free space accounting conforming to the dynamic align
> setting.
>
> Reported-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
> Reported-by: Jeff Moyer <jmoyer@redhat.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
> Link: https://lore.kernel.org/r/158041478371.3889308.14542630147672668068.stgit@dwillia2-desk3.amr.corp.intel.com
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>

This looks good to me.

Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
_______________________________________________
Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org
To unsubscribe send an email to linux-nvdimm-leave@lists.01.org

  reply index

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-13  0:48 [PATCH v2 0/4] libnvdimm: Cross-arch compatible namespace alignment Dan Williams
2020-02-13  0:48 ` [PATCH v2 1/4] mm/memremap_pages: Introduce memremap_compat_align() Dan Williams
2020-02-13 16:57   ` Jeff Moyer
2020-02-13 18:26     ` Dan Williams
2020-02-14  3:26       ` Aneesh Kumar K.V
2020-02-14 20:59       ` Jeff Moyer
2020-02-14 23:05         ` Dan Williams
2020-02-13  0:48 ` [PATCH v2 2/4] libnvdimm/namespace: Enforce memremap_compat_align() Dan Williams
2020-02-13 19:16   ` Jeff Moyer
2020-02-13 21:55   ` Jeff Moyer
2020-02-13 22:43     ` Dan Williams
2020-02-14 16:44       ` Jeff Moyer
2020-02-14 16:55         ` Aneesh Kumar K.V
2020-02-13  0:48 ` [PATCH v2 3/4] libnvdimm/region: Introduce NDD_LABELING Dan Williams
2020-02-13 19:12   ` Jeff Moyer
2020-02-13  0:48 ` [PATCH v2 4/4] libnvdimm/region: Introduce an 'align' attribute Dan Williams
2020-02-14 20:19   ` Jeff Moyer [this message]
2020-02-14 21:03 ` [PATCH v2 0/4] libnvdimm: Cross-arch compatible namespace alignment Jeff Moyer

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=x495zg8exc4.fsf@segfault.boston.devel.redhat.com \
    --to=jmoyer@redhat.com \
    --cc=aneesh.kumar@linux.ibm.com \
    --cc=dan.j.williams@intel.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-nvdimm@lists.01.org \
    --cc=linuxppc-dev@lists.ozlabs.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-NVDIMM Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-nvdimm/0 linux-nvdimm/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-nvdimm linux-nvdimm/ https://lore.kernel.org/linux-nvdimm \
		linux-nvdimm@lists.01.org
	public-inbox-index linux-nvdimm

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.01.lists.linux-nvdimm


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git