HP c-Class Performance Tuning manual To avoid this issue. For more information, see the patch

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to avoid this issue. For more information, see the patch

(http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=b90f687018e6d6) and bug report (https://bugzilla.kernel.org/show_bug.cgi?id=15579).

The fix is included in RHEL6 pre-release kernel kernel-2.6.32-23.el6. The eventual release RHEL6 kernel is not affected by this issue.

Discard support was added to the kernel.org mainline ext4 in Version 2.6.28 and was enabled by default. For fear of damaging some devices, discard was set to default to disabled in Version 2.6.33-rc1 and was back ported to 2.6.31.8 and 2.6.32.1. For more information, see the kernel patch (http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=5328e635315734d).

Debugging performance issues 15

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Contents HP IO Accelerator Performance Tuning Guide Page Contents Setting Windows driver affinity Introduction About the Performance and Tuning GuideVerifying Linux system performance System performanceWrite bandwidth test System performance Verifying Windows system performance with Iometer Debugging performance issues Improperly configured benchmarkOversubscribed bus Handling PCIe errors PCIe link width improperly negotiated CPU thermal throttling or auto-idling Slow performance using RAID5 on Linux Using CP and other system utilitiesBenchmarking through a filesystem To avoid this issue. For more information, see the patch General tuning techniques Using direct I/O, unbuffered, or zero copyMultiple outstanding IOs $ dd if=/dev/zero of=/dev/fioX bs=10M oflag=direct Pre-conditioning$ echo 4096 /sys/block/fio name/queue/nrrequests Pre-allocating memoryPreallocatemb Increased steady-state write performance with fio-format Tuning techniques for writesStripewidth = dbd * stride Linux filesystem tuningExt2-3-4 tuning Stride = chunk size / filesystem block sizeOptions iomemory-vsl preallocatememory=1072,4997,6710,10345 Using the IO Accelerator as swap spaceFio benchmark Compiling the fio benchmark$ tar xjvf fio-X.Y.Z.tar.bz2 $ cd fio-X.Y.Z Page Fd = openfilename, Owronly Odirect Programming using direct I/OUsing direct I/O on Linux Fd = openfilename, OwronlyUsing direct I/O on Windows ++ code sample Programming using direct I/O Programming using direct I/O Windows driver affinity Setting Windows driver affinityCreate the SetWorkerAffinity2 tag of type Regdword Acronyms and abbreviations Index Index