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sys_attrs_alt(5)
NAME
  sys_attrs_alt - alt subsystem attributes

DESCRIPTION
  This reference page lists and describes attributes for the alt (alt) kernel
  subsystem. This subsystem is used by the DEGPA Gigabit Ethernet network
  interface cards (NICs). The hardware and firmware for these cards support
  coalescing, a threshold that causes the driver to send an interrupt to the
  kernel. This threshold can be defined in terms of a timer or the number of
  packets sent or received. The *_coal and *_ticks attributes in the
  following list support performance tuning related to coalescing.

  Refer to sys_attrs(5) for an introduction to the topic of kernel subsystem
  attributes.

  DriverVersion
      The version number of the alt driver.  This is a read-only attribute,
      and cannot be changed.

  FirmwareVersion
      The version number of the firmware that is downloaded to the DEGPA
      Gigabit Ethernet card.  This is a read-only attribute and cannot be
      changed.

  minimal_isr
      A value that enables (1) or disables (0) the awakening of separate
      threads by the driver's interrupt service routine to handle completion
      of transmit and receive operations. When separate worker threads are
      enabled, the system load of the Gigabit Ethernet driver can be spread
      over multiple CPUs. When separate worker threads are disabled, the
      master system CPU (or the master CPU in each RAD of a NUMA system)
      services all the transmit and receive operations for the system's DEGPA
      Gigabit Ethernet adapters.

      Default: 1 (multiple threads enabled)

      A 0 setting improves the performance of the driver software itself.
      However, overall system performance is likely to suffer during times of
      high network load because kernel applications other than the driver can
      have difficulty accessing the master CPU. Furthermore, the likelihood
      of overall system performance degradation goes up with each additional
      DEGPA Gigabit Ethernet card supported by the system. For this reason,
      the default setting (1) is recommended for most systems and
      applications.

  * recv_coal
      The number of packets that are sent before an interrupt is generated
      (assuming that the recv_ticks timer does not expire first).

      Default: 32 (packets)

      Minimum: 0

      Maximum: 511

      This attribute can be modified at run time.

  * RecvDmaBurst
      The receive DMA burst size (in longwords) for the DEGPA Gigabit
      Ethernet card. The default value (0) specifies that the receive DMA
      burst size is set to be the maximum supported by the Gigabit Ethernet
      card.

      Although this attribute can be modified at run time, do not change it
      unless instructed to do so by support personnel or patch kit
      instructions.

  * recv_ticks
      The number of microseconds (usec) that elapse after receipt of the last
      packet before an interrupt is generated (assuming that the recv_coal
      threshold is not reached first).

      Default: 200 (usec)

      Minimum: 0

      Maximum: 888,888

      This attribute can be modified at run time.

  * send_coal
      The number of packets that are sent before an interrupt is generated
      (assuming that the send_ticks timer does not expire first).

      Default: 32 (packets)

      Minimum: 0

      Maximum: 511

      This attribute can be modified at run time.

  * send_ticks
      The number of microseconds (usec) that elapse after transmission of the
      last packet before an interrupt is generated (assuming that the
      send_coal threshold is not reached first).

      Default: 125,000 (usec)

      Minimum: 0

      Maximum: 888,888

      This attribute can be modified at run time.

      The default value of the send_ticks attribute might have a negative
      performance impact on applications using NFSv3. For these applications,
      it is recommended that send_ticks be lowered to 10. Depending on the
      results from continued testing with a wide variety of applications and
      systems, 10 might be the default value for send_ticks in a future
      release.

  * XmitDmaBurst
      The transmit DMA burst size (in longwords) for the DEGPA Gigabit
      Ethernet card. The default value (0) specifies that the transmit DMA
      burst size is set to be the maximum supported by the Gigabit Ethernet
      card.

      Although this attribute can be modified at run time, do not change it
      unless instructed to do so by support personnel or patch kit
      instructions.

SEE ALSO
  sys_attrs(5)

Index for Section 5

Alphabetical listing for S

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