From: "Kani, Toshimitsu" <toshi.kani-ZPxbGqLxI0U@public.gmane.org> To: "snitzer-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org" <snitzer-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> Cc: "axboe-tSWWG44O7X1aa/9Udqfwiw@public.gmane.org" <axboe-tSWWG44O7X1aa/9Udqfwiw@public.gmane.org>, "linux-nvdimm-y27Ovi1pjclAfugRpC6u6w@public.gmane.org" <linux-nvdimm-y27Ovi1pjclAfugRpC6u6w@public.gmane.org>, "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, "dm-devel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org" <dm-devel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, "viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org" <viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org> Subject: Re: [PATCH v3 3/4] dm: add infrastructure for DAX support Date: Fri, 24 Jun 2016 15:40:24 +0000 [thread overview] Message-ID: <1466782822.3504.391.camel@hpe.com> (raw) In-Reply-To: <20160624014930.GA10540-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> On Thu, 2016-06-23 at 21:49 -0400, Mike Snitzer wrote: > On Thu, Jun 23 2016 at 7:36pm -0400, > Kani, Toshimitsu <toshi.kani@hpe.com> wrote: : > > Thanks for the update. I have a question about the above change. Targets > > may have their own parameters. For instance, dm-stripe has 'chunk_size', > > which is checked in stripe_ctr(). DAX adds additional restriction that > > chunk_size needs to be aligned by page size. So, I think we need to keep > > target responsible to verify if DAX can be supported. What do you think? > > We've never had to concern the dm-stripe target with hardware > specific chunk_size validation. The user is able to specify the > chunk_size via lvm2's lvcreate -I argument. Yes this gives users enough > rope to hang themselves but it is very easy to configure a dm-stripe > device with the appropriate chunk size (PAGE_SIZE) from userspace. > > But lvm2 could even be trained to make sure the chunk_size is a factor > of physical_block_size (PAGE_SIZE in the case of pmem) if the underlying > devices export queue/dax=1 lvcreate -I only allows multiple of page size, so we are OK with lvm2. I was wondering if the check in lvm2 is enough. Are there any other tools that may be used to configure stripe size? Can we trust userspace on this? Thanks, -Toshi _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm
WARNING: multiple messages have this Message-ID (diff)
From: "Kani, Toshimitsu" <toshi.kani@hpe.com> To: "snitzer@redhat.com" <snitzer@redhat.com> Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "linux-nvdimm@ml01.01.org" <linux-nvdimm@ml01.01.org>, "viro@zeniv.linux.org.uk" <viro@zeniv.linux.org.uk>, "dan.j.williams@intel.com" <dan.j.williams@intel.com>, "axboe@kernel.dk" <axboe@kernel.dk>, "ross.zwisler@linux.intel.com" <ross.zwisler@linux.intel.com>, "dm-devel@redhat.com" <dm-devel@redhat.com>, "yigal@plexistor.com" <yigal@plexistor.com> Subject: Re: [PATCH v3 3/4] dm: add infrastructure for DAX support Date: Fri, 24 Jun 2016 15:40:24 +0000 [thread overview] Message-ID: <1466782822.3504.391.camel@hpe.com> (raw) In-Reply-To: <20160624014930.GA10540@redhat.com> On Thu, 2016-06-23 at 21:49 -0400, Mike Snitzer wrote: > On Thu, Jun 23 2016 at 7:36pm -0400, > Kani, Toshimitsu <toshi.kani@hpe.com> wrote: : > > Thanks for the update. I have a question about the above change. Targets > > may have their own parameters. For instance, dm-stripe has 'chunk_size', > > which is checked in stripe_ctr(). DAX adds additional restriction that > > chunk_size needs to be aligned by page size. So, I think we need to keep > > target responsible to verify if DAX can be supported. What do you think? > > We've never had to concern the dm-stripe target with hardware > specific chunk_size validation. The user is able to specify the > chunk_size via lvm2's lvcreate -I argument. Yes this gives users enough > rope to hang themselves but it is very easy to configure a dm-stripe > device with the appropriate chunk size (PAGE_SIZE) from userspace. > > But lvm2 could even be trained to make sure the chunk_size is a factor > of physical_block_size (PAGE_SIZE in the case of pmem) if the underlying > devices export queue/dax=1 lvcreate -I only allows multiple of page size, so we are OK with lvm2. I was wondering if the check in lvm2 is enough. Are there any other tools that may be used to configure stripe size? Can we trust userspace on this? Thanks, -Toshi
next prev parent reply other threads:[~2016-06-24 15:40 UTC|newest] Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-06-23 21:05 [PATCH v3 0/4] Support DAX for device-mapper linear devices Mike Snitzer 2016-06-23 21:05 ` Mike Snitzer [not found] ` <1466715953-40692-1-git-send-email-snitzer-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> 2016-06-23 21:05 ` [PATCH v3 1/4] block: add QUEUE_FLAG_DAX for devices to advertise their DAX support Mike Snitzer 2016-06-23 21:05 ` Mike Snitzer 2016-06-23 21:05 ` [PATCH v3 2/4] block: expose QUEUE_FLAG_DAX in sysfs Mike Snitzer 2016-06-23 21:05 ` Mike Snitzer 2016-06-23 21:05 ` [PATCH v3 3/4] dm: add infrastructure for DAX support Mike Snitzer 2016-06-23 21:05 ` Mike Snitzer [not found] ` <1466715953-40692-4-git-send-email-snitzer-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> 2016-06-23 23:36 ` Kani, Toshimitsu 2016-06-23 23:36 ` Kani, Toshimitsu [not found] ` <1466724984.3504.380.camel-ZPxbGqLxI0U@public.gmane.org> 2016-06-24 1:49 ` Mike Snitzer 2016-06-24 1:49 ` Mike Snitzer [not found] ` <20160624014930.GA10540-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> 2016-06-24 15:40 ` Kani, Toshimitsu [this message] 2016-06-24 15:40 ` Kani, Toshimitsu [not found] ` <1466782822.3504.391.camel-ZPxbGqLxI0U@public.gmane.org> 2016-06-24 15:44 ` Mike Snitzer 2016-06-24 15:44 ` Mike Snitzer [not found] ` <20160624154446.GB13898-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> 2016-06-24 15:56 ` Kani, Toshimitsu 2016-06-24 15:56 ` Kani, Toshimitsu 2016-06-23 21:05 ` [PATCH v3 4/4] dm linear: add " Mike Snitzer 2016-06-23 21:05 ` Mike Snitzer 2016-06-30 17:00 ` [PATCH v3 0/4] Support DAX for device-mapper linear devices Mike Snitzer 2016-06-30 17:00 ` Mike Snitzer [not found] ` <20160630170053.GA20750-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> 2016-07-08 19:30 ` Mike Snitzer 2016-07-08 19:30 ` Mike Snitzer
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