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

Parinay Kondekar parinay_kondekar at xyratex.com
Mon Apr 7 08:18:39 PDT 2014


On 7 April 2014 17:46, aayush agrawal <aayush.agrawal at calsoftinc.com> wrote:

>  Hi,
>
> Following are few questions which still remain unanswered:
>
>
>    1. I am seeing that 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?
>
> Little searching gave me this - https://jira.hpdd.intel.com/browse/LU-535
 / http://review.whamcloud.com/#/c/1142/ .



>
>    1. If I am correct this code gets invoked from following location from
>    obdfilter(correct me if I am wrong):
>       1. lustre/obdfilter/filter_io_26.c line
>       no:367
>        &
>       nbsp;                                                                                                                                                                    &
>       nbsp;&nb sp;                                       <snip>
>
>                         /* I only set the page to be constant only if it
>                          * is mapped to a contiguous underlying disk
> block(s).
>                          * It will then make sure the corresponding device
>                          * cache of raid5 will be overwritten by this page.
>                          * - jay */
>                         if ((rw == OBD_BRW_WRITE) &&
>                             (nblocks == blocks_per_page) &&
>
> mapping_cap_page_constant_write(inode->i_mapping))
>                                SetPageConstant(page);
>
>                     </snip>
>
>    1. I want to use this zero copy patch in latest lustre 2.5.0(With
>    kernel linux-2.6.32-358.18.1.el6). I could port patch to this latest
>    kernel. But it looks like obdfilter module has been replaced in latest
>    kernel which used to invoke zero copy changes as mentioned in point 2. I
>    think its ofd module with which it got replaced(??). So latest lustre is
>    not able to invoke zero copy changes(for eg: setting/clearing PG_constant
>    etc.). Is there any different patch available for invoking these zero copy
>    changes?
>    2. Can you also suggest which newly added module in lustre-2.5.0 would
>    require these changes?
>
>
> Thanks,
> Aayush
>
>
> On 4/7/2014 4:50 PM, aayush agrawal wrote:
>
> Hi,
>
> I got both the errors resolved. Looks like there was some issue with my
> lustre build process itself.
> So I think along with raid5-zerocopy-rhel6.patch, raid5-stats-rhel6.patch
> was the only additional patch required.
>
> Thanks,
> Aayush
>
> On 3/24/2014 8:40 PM, aayush agrawal wrote:
>
> 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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