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OpenCloudOS-Kernel/Documentation/ABI/testing/sysfs-driver-xen-blkfront

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xen-blkfront: Apply changed parameter name to the document Commit 14e710fe7897 ("xen-blkfront: rename indirect descriptor parameter") changed the name of the module parameter for the maximum amount of segments in indirect requests but missed updating the document. This commit updates the document. Signed-off-by: SeongJae Park <sjpark@amazon.de> Reviewed-by: Juergen Gross <jgross@suse.com> Acked-by: Roger Pau Monné <roger.pau@citrix.com> Link: https://lore.kernel.org/r/20200923061841.20531-4-sjpark@amazon.com Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2020-09-23 14:18:41 +08:00
What: /sys/module/xen_blkfront/parameters/max_indirect_segments
xen-blkfront: Introduce a 'max' module parameter to alter the amount of indirect segments. The max module parameter (by default 32) is the maximum number of segments that the frontend will negotiate with the backend for indirect descriptors. Higher value means more potential throughput but more memory usage. The backend picks the minimum of the frontend and its default backend value. Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2013-05-15 22:39:34 +08:00
Date: June 2013
KernelVersion: 3.11
Contact: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Description:
Maximum number of segments that the frontend will negotiate
with the backend for indirect descriptors. The default value
is 32 - higher value means more potential throughput but more
memory usage. The backend picks the minimum of the frontend
and its default backend value.
xen-blkfront: add a parameter for disabling of persistent grants Persistent grants feature provides high scalability. On some small systems, however, it could incur data copy overheads[1] and thus it is required to be disabled. It can be disabled from blkback side using a module parameter, 'feature_persistent'. But, it is impossible from blkfront side. For the reason, this commit adds a blkfront module parameter for disabling of the feature. [1] https://wiki.xen.org/wiki/Xen_4.3_Block_Protocol_Scalability Signed-off-by: SeongJae Park <sjpark@amazon.de> Reviewed-by: Juergen Gross <jgross@suse.com> Acked-by: Roger Pau Monné <roger.pau@citrix.com> Link: https://lore.kernel.org/r/20200923061841.20531-3-sjpark@amazon.com Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2020-09-23 14:18:40 +08:00
What: /sys/module/xen_blkfront/parameters/feature_persistent
Date: September 2020
KernelVersion: 5.10
xen-blk{back,front}: Update contact points for buffer_squeeze_duration_ms and feature_persistent SeongJae is currently listed as a contact point for some blk{back,front} features, but he will not work for XEN for a while. This commit therefore updates the contact point to his colleague, Maximilian, who is understanding the context and actively working with the features now. Signed-off-by: SeongJae Park <sj@kernel.org> Signed-off-by: Maximilian Heyne <mheyne@amazon.de> Acked-by: Roger Pau Monné <roger.pau@citrix.com> Link: https://lore.kernel.org/r/20220420072734.1692-1-sj@kernel.org Signed-off-by: Juergen Gross <jgross@suse.com>
2022-04-20 15:27:34 +08:00
Contact: Maximilian Heyne <mheyne@amazon.de>
xen-blkfront: add a parameter for disabling of persistent grants Persistent grants feature provides high scalability. On some small systems, however, it could incur data copy overheads[1] and thus it is required to be disabled. It can be disabled from blkback side using a module parameter, 'feature_persistent'. But, it is impossible from blkfront side. For the reason, this commit adds a blkfront module parameter for disabling of the feature. [1] https://wiki.xen.org/wiki/Xen_4.3_Block_Protocol_Scalability Signed-off-by: SeongJae Park <sjpark@amazon.de> Reviewed-by: Juergen Gross <jgross@suse.com> Acked-by: Roger Pau Monné <roger.pau@citrix.com> Link: https://lore.kernel.org/r/20200923061841.20531-3-sjpark@amazon.com Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2020-09-23 14:18:40 +08:00
Description:
Whether to enable the persistent grants feature or not. Note
xen-blkfront: Apply 'feature_persistent' parameter when connect In some use cases[1], the backend is created while the frontend doesn't support the persistent grants feature, but later the frontend can be changed to support the feature and reconnect. In the past, 'blkback' enabled the persistent grants feature since it unconditionally checked if frontend supports the persistent grants feature for every connect ('connect_ring()') and decided whether it should use persistent grans or not. However, commit aac8a70db24b ("xen-blkback: add a parameter for disabling of persistent grants") has mistakenly changed the behavior. It made the frontend feature support check to not be repeated once it shown the 'feature_persistent' as 'false', or the frontend doesn't support persistent grants. Similar behavioral change has made on 'blkfront' by commit 74a852479c68 ("xen-blkfront: add a parameter for disabling of persistent grants"). This commit changes the behavior of the parameter to make effect for every connect, so that the previous behavior of 'blkfront' can be restored. [1] https://lore.kernel.org/xen-devel/CAJwUmVB6H3iTs-C+U=v-pwJB7-_ZRHPxHzKRJZ22xEPW7z8a=g@mail.gmail.com/ Fixes: 74a852479c68 ("xen-blkfront: add a parameter for disabling of persistent grants") Cc: <stable@vger.kernel.org> # 5.10.x Signed-off-by: SeongJae Park <sj@kernel.org> Reviewed-by: Maximilian Heyne <mheyne@amazon.de> Reviewed-by: Juergen Gross <jgross@suse.com> Link: https://lore.kernel.org/r/20220715225108.193398-4-sj@kernel.org Signed-off-by: Juergen Gross <jgross@suse.com>
2022-07-16 06:51:08 +08:00
that this option only takes effect on newly connected frontends.
xen-blkfront: add a parameter for disabling of persistent grants Persistent grants feature provides high scalability. On some small systems, however, it could incur data copy overheads[1] and thus it is required to be disabled. It can be disabled from blkback side using a module parameter, 'feature_persistent'. But, it is impossible from blkfront side. For the reason, this commit adds a blkfront module parameter for disabling of the feature. [1] https://wiki.xen.org/wiki/Xen_4.3_Block_Protocol_Scalability Signed-off-by: SeongJae Park <sjpark@amazon.de> Reviewed-by: Juergen Gross <jgross@suse.com> Acked-by: Roger Pau Monné <roger.pau@citrix.com> Link: https://lore.kernel.org/r/20200923061841.20531-3-sjpark@amazon.com Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2020-09-23 14:18:40 +08:00
The default is Y (enable).