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  1. Mar 15, 2016
  3. Mar 11, 2016
  5. Mar 10, 2016
  7. Mar 09, 2016
    • Manoj N. Kumar's avatar
      cxlflash: Increase cmd_per_lun for better throughput · 83430833
      Manoj N. Kumar authored 
      

With the current value of cmd_per_lun at 16, the throughput
over a single adapter is limited to around 150kIOPS.

Increase the value of cmd_per_lun to 256 to improve
throughput. With this change a single adapter is able to
attain close to the maximum throughput (380kIOPS).
Also change the number of RRQ entries that can be queued.

Signed-off-by: default avatarManoj N. Kumar <manoj@linux.vnet.ibm.com>
Acked-by: default avatarMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Reviewed-by: default avatarUma Krishnan <ukrishn@linux.vnet.ibm.com>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
      83430833
    • Manoj N. Kumar's avatar
      cxlflash: Fix to avoid unnecessary scan with internal LUNs · 603ecce9
      Manoj N. Kumar authored 
      

When switching to the internal LUN defined on the
IBM CXL flash adapter, there is an unnecessary
scan occurring on the second port. This scan leads
to the following extra lines in the log:

Dec 17 10:09:00 tul83p1 kernel: [ 3708.561134] cxlflash 0008:00:00.0: cxlflash_queuecommand: (scp=c0000000fc1f0f00) 11/1/0/0 cdb=(A0000000-00000000-10000000-00000000)
Dec 17 10:09:00 tul83p1 kernel: [ 3708.561147] process_cmd_err: cmd failed afu_rc=32 scsi_rc=0 fc_rc=0 afu_extra=0xE, scsi_extra=0x0, fc_extra=0x0

By definition, both of the internal LUNs are on the first port/channel.

When the lun_mode is switched to internal LUN the
same value for host->max_channel is retained. This
causes an unnecessary scan over the second port/channel.

This fix alters the host->max_channel to 0 (1 port), if internal
LUNs are configured and switches it back to 1 (2 ports) while
going back to external LUNs.

Signed-off-by: default avatarManoj N. Kumar <manoj@linux.vnet.ibm.com>
Acked-by: default avatarMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Reviewed-by: default avatarUma Krishnan <ukrishn@linux.vnet.ibm.com>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
      603ecce9
    • Uma Krishnan's avatar
      cxlflash: Reorder user context initialization · 5d1952ac
      Uma Krishnan authored 
      

In order to support cxlflash in the PowerVM environment, underlying
hypervisor APIs have imposed a kernel API ordering change.

For the superpipe access to LUN, user applications need a context.
The cxlflash module creates this context by making a sequence of
cxl calls. In the current code, a context is initialized via
cxl_dev_context_init() followed by cxl_process_element(), a function
that obtains the process element id. Finally, cxl_start_work()
is called to attach the process element.

In the PowerVM environment, a process element id cannot be obtained
from the hypervisor until the process element is attached. The
cxlflash module is unable to create contexts without a valid
process element id.

To fix this problem, cxl_start_work() is called before obtaining
the process element id.

Signed-off-by: default avatarUma Krishnan <ukrishn@linux.vnet.ibm.com>
Acked-by: default avatarMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
      5d1952ac
    • Matthew R. Ochs's avatar
      cxlflash: Simplify attach path error cleanup · 8a96b52a
      Matthew R. Ochs authored 
      

The cxlflash_disk_attach() routine currently uses a cascading error
gate strategy for its error cleanup path. While this strategy is
commonly used to handle cleanup scenarios, it is too restrictive when
function callouts need to be restructured. Problems range from
inserting error path bugs in previously 'good' code to the cleanup
path imposing design changes to how the normal path is structured.
A less restrictive approach is needed to support ordering changes
that come about when operating in different environments.

To overcome this restriction, the error cleanup path is modified to
have a single entrypoint and use conditional logic to cleanup where
necessary. Entities that require multiple cleanup steps must be
carefully vetted to ensure their APIs support state. In cases where
they do not (none as of this commit) additional local variables can
be used to maintain state on their behalf.

Signed-off-by: default avatarMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Reviewed-by: default avatarUma Krishnan <ukrishn@linux.vnet.ibm.com>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
      8a96b52a
    • Matthew R. Ochs's avatar
      cxlflash: Split out context initialization · 5e6632d1
      Matthew R. Ochs authored 
      

Presently, context information structures are allocated and
initialized in the same routine, create_context(). This imposes
an ordering restriction such that all pieces of information needed
to initialize a context must be known before the context is even
allocated.

This design point is not flexible when the order of context
creation needs to be modified. Specifically, this can lead to
problems when members of the context information structure are
a part of an ordering dependency (i.e. - the 'work' structure
embedded within the context).

To remedy, the allocation is left as-is, inside of the existing
create_context() routine and the initialization is transitioned
to a new void routine, init_context(). At the same time, in
anticipation of these routines not being called in sequence, a
state boolean is added to the context information structure to
track when the context has been initilized. The context teardown
routine, destroy_context(), is modified to support being called
with a non-initialized context.

Signed-off-by: default avatarMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Reviewed-by: default avatarUma Krishnan <ukrishn@linux.vnet.ibm.com>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
      5e6632d1
    • Uma Krishnan's avatar
      cxlflash: Unmap problem state area before detaching master context · 6ded8b3c
      Uma Krishnan authored 
      

When operating in the PowerVM environment, the cxlflash module can
receive an error from the hypervisor indicating that there are
existing mappings in the page table for the process MMIO space.

This issue exists because term_afu() currently invokes term_mc()
before stop_afu(), allowing for the master context to be detached
first and the problem state area to be unmapped second.

To resolve this issue, stop_afu() should be called before term_mc().

Signed-off-by: default avatarUma Krishnan <ukrishn@linux.vnet.ibm.com>
Acked-by: default avatarMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
      6ded8b3c
    • Manoj N. Kumar's avatar
      cxlflash: Simplify PCI registration · 961487e4
      Manoj N. Kumar authored 
      

The calls to pci_request_regions(), pci_resource_start(),
pci_set_dma_mask(), pci_set_master() and pci_save_state() are all
unnecessary for the IBM CXL flash adapter since data buffers
are not required to be mapped to the device's memory.

The use of services such as pci_set_dma_mask() are problematic on
hypervisor managed systems as the IBM CXL flash adapter is operating
under a virtual PCI Host Bridge (virtual PHB) which does not support
these services.

cxlflash 0001:00:00.0: init_pci: Failed to set PCI DMA mask rc=-5

The resolution is to simplify init_pci(), to a point where it does the
bare minimum (pci_enable_device). Similarly, remove the call the
pci_release_regions() from cxlflash_remove().

Signed-off-by: default avatarManoj N. Kumar <manoj@linux.vnet.ibm.com>
Acked-by: default avatarMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Reviewed-by: default avatarUma Krishnan <ukrishn@linux.vnet.ibm.com>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
      961487e4
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