HP Tru64 UNIX - aio Related Performance Issue



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 Advisory Information

RELEASE DATE: 22 March 2004

UPDATE DATE: 3 August 2004


Update of 3-Aug-04:
This Engineering Advisory is being updated to reflect a change in the associated V5.1A BL6 (PK4) ERP kit name. Due to a kitting problem, a new kit had to be built.

This V5.1A BL24 (PK6) and V5.1B BL24 (PK3) Early Release Patch (ERP) contains fixes for the following two aio-related issues:

  • HP Tru64 UNIX - aio Related Performance Issue, described in this EA

New code introduced into V5.1A BL24 (PK6) and V5.1B BL24 (PK3) to prevent an aio-related application deadlock has the potential to increase contention for the vm_umap lock.  This lock contention could severely reduce aio throughput.  This ERP corrects the new code introduced in BL24.  It provides an improvement on the aio contention logic to reduce the occurrence of lock contention.

  • HP Tru64 UNIX - file region locks (set via fcntl or flock) can be inadvertently released as a result of AIO processing (BU040223_EW02)

The BL24 ERPs distributed earlier in BU040223_EW02 modify std_kern.mod.  The code to correct the aio related performance issue, described in this EA, also modifies std_kern.mod.  Therefore, to avoid installation conflicts, the BL24 ERPs from both EAs have been merged.

The BL22 and BL23 ERPs distributed in BU040223_EW02 remain valid.

Customers whose systems run large scale database applications utilizing asynchronous I/O are encouraged to install this ERP.


The following versions are affected:

  • HP Tru64 UNIX V5.1B PK3 (BL24)
  • HP Tru64 UNIX V5.1A PK6 (BL24)

HP is releasing the following Early Release Patch kits (ERPs) publicly for use by any customer.  The ERP kits use dupatch to install and will not install over any Customer Specific Patches (CSPs) that have file intersections with the ERP.  Contact your service provider for assistance if the installation of the ERP is blocked by any of your installed CSPs.

The BL24 ERPs identified in this EA will successfully install over the BL24 ERPs delivered in BU040223_EW02.

The performance related fix contained in the ERP kits is scheduled to be available in the following mainstream releases:

  • HP Tru64 UNIX V5.1B PK4 (BL25)
  • HP Tru64 UNIX V5.1A PK7 (BL26)

Early Release Patch Kits

ERP kits are available for the following versions. The kits distribute the following file:


HP Tru64 UNIX 5.1B
Prerequsite:      HP Tru64 UNIX 5.1B PK3 (BL24)
ERP Kit Name:          T64KIT0021909-V51BB24-E-20040317.tar
ITRC Patch Page:  http://www.itrc.hp.com/service/patch/mainPage.do
Kit Location:  

HP Tru64 UNIX 5.1A
Prerequsite: HP Tru64 UNIX 5.1A PK6 (BL24)
ERP Kit Name: T64KIT0022125-V51AB24-E-20040414
ITRC Patch Page: http://www.itrc.hp.com/service/patch/mainPage.do
Kit Location: http://www.itrc.hp.com/service/patch/patchDetail.do?patchid=T64KIT0022125-V51AB24-E-20040414