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 [thread overview]
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>
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WARNING: multiple messages have this Message-ID (diff)
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>,
vishal.l.verma@intel.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 [thread overview]
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>
WARNING: multiple messages have this Message-ID (diff)
From: Jeff Moyer <jmoyer@redhat.com>
To: Dan Williams <dan.j.williams@intel.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
vishal.l.verma@intel.com, linuxppc-dev@lists.ozlabs.org,
linux-kernel@vger.kernel.org, linux-nvdimm@lists.01.org
Subject: Re: [PATCH v2 4/4] libnvdimm/region: Introduce an 'align' attribute
Date: Fri, 14 Feb 2020 15:19:07 -0500 [thread overview]
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>
next prev parent reply other threads:[~2020-02-14 20:19 UTC|newest]
Thread overview: 54+ 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 ` Dan Williams
2020-02-13 0:48 ` Dan Williams
2020-02-13 0:48 ` [PATCH v2 1/4] mm/memremap_pages: Introduce memremap_compat_align() Dan Williams
2020-02-13 0:48 ` Dan Williams
2020-02-13 0:48 ` Dan Williams
2020-02-13 16:57 ` Jeff Moyer
2020-02-13 16:57 ` Jeff Moyer
2020-02-13 16:57 ` Jeff Moyer
2020-02-13 18:26 ` Dan Williams
2020-02-13 18:26 ` Dan Williams
2020-02-13 18:26 ` Dan Williams
2020-02-14 3:26 ` Aneesh Kumar K.V
2020-02-14 3:26 ` Aneesh Kumar K.V
2020-02-14 3:26 ` Aneesh Kumar K.V
2020-02-14 20:59 ` Jeff Moyer
2020-02-14 20:59 ` Jeff Moyer
2020-02-14 20:59 ` Jeff Moyer
2020-02-14 23:05 ` Dan Williams
2020-02-14 23:05 ` Dan Williams
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 0:48 ` Dan Williams
2020-02-13 0:48 ` Dan Williams
2020-02-13 19:16 ` Jeff Moyer
2020-02-13 19:16 ` Jeff Moyer
2020-02-13 19:16 ` Jeff Moyer
2020-02-13 21:55 ` Jeff Moyer
2020-02-13 21:55 ` Jeff Moyer
2020-02-13 21:55 ` Jeff Moyer
2020-02-13 22:43 ` Dan Williams
2020-02-13 22:43 ` Dan Williams
2020-02-13 22:43 ` Dan Williams
2020-02-14 16:44 ` Jeff Moyer
2020-02-14 16:44 ` Jeff Moyer
2020-02-14 16:44 ` Jeff Moyer
2020-02-14 16:55 ` Aneesh Kumar K.V
2020-02-14 16:55 ` Aneesh Kumar K.V
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 0:48 ` Dan Williams
2020-02-13 0:48 ` Dan Williams
2020-02-13 19:12 ` Jeff Moyer
2020-02-13 19:12 ` Jeff Moyer
2020-02-13 19:12 ` Jeff Moyer
2020-02-13 0:48 ` [PATCH v2 4/4] libnvdimm/region: Introduce an 'align' attribute Dan Williams
2020-02-13 0:48 ` Dan Williams
2020-02-13 0:48 ` Dan Williams
2020-02-14 20:19 ` Jeff Moyer [this message]
2020-02-14 20:19 ` Jeff Moyer
2020-02-14 20:19 ` Jeff Moyer
2020-02-14 21:03 ` [PATCH v2 0/4] libnvdimm: Cross-arch compatible namespace alignment Jeff Moyer
2020-02-14 21:03 ` Jeff Moyer
2020-02-14 21:03 ` Jeff Moyer
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