[Lustre-discuss] Facing issues in applying zero copy patch on rhel6.

[aayush agrawal]

Hi,

I wanted to apply zero copy patch on rhel6 so I followed below steps:

 1. Downloaded lustre-2.1.2 and corresponding kernel
    rpm(linux-2.6.32-220.17.1.el6). The OS I am using is CentOS 6.4.
 2. Applied kernel patches from lustre source code to kernel.
 3. Downloaded a zero copy patch for rhel6 from:
    https://github.com/Xyratex/lustre-stable/blob/b_neo_1.4.0/lustre/kernel_patches/patches/raid5-zerocopy-rhel6.patch
 4. Applied this patch to above kernel.
 5. Then I tried to compile this kernel but it gives undefined symbol
    errors for writes_zcopy and PageConstant.
     1. For writes_zcopy I found another patch on the same git hub link:
        https://github.com/Xyratex/lustre-stable/blob/b_neo_1.4.0/lustre/kernel_patches/patches/raid5-stats-rhel6.patch.
     2. For PageConstant I couldn't find any patch to rectify this
        error. Even I do not see usage of PG_Constant/SetPageConstant
        etc. in raid5-zerocopy-rhel6.patch which I think is essential.
 6. So my questions are:
     1. I think few patches are missing here. As mentioned above one of
        them would be raid5-stats-rhel6.patch please confirm.
     2. if confirmed, still there has to be at least one patch missing
        (to include PageConstant use). Are there any other patches to be
        applied before I apply raid5-stats-rhel6.patch and
        raid5-zerocopy-rhel6.patch.
     3. I am seeing that this zero copy patch existed in lustre-2.1.2,
        In lustre/kernel-patches/patches directory for rhel5. But it has
        been removed in latest lustre 2.5.0. Is there any specific
        reason to remove it.

Thanks,
Aayush








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