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  1. RHEL
  2. RHEL-93320

glibc: Backport request for _dl_find_object to RHEL 9

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    • glibc-2.34-216.el9
    • None
    • 2
    • rhel-pt-c-libs
    • ssg_platform_tools
    • 3
    • False
    • False
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    • Yes
    • Red Hat Enterprise Linux for SAP Solutions
    • PT Libraries 2025 S09, PT Libraries 2025 S10
    • Enhancement
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      .Improved Exception Handling Performance in ‎`glibc`

      Previously, exception handling in large applications was slow, which impacted performance, particularly in environments with a high volume of users or frequent exceptions. This was due to the time spent in the ‎`__dl_iterate_phdr` function, called from ‎`_Unwind_Find_FDE`.

      With this update, the exception handling algorithm in `glibc` has been improved to enhance exception processing speed. The update introduces new symbols to the ABI as part of GLIBC_2.35, including ‎`__epoll_pwait2_time64`, ‎`__memcmpeq`, ‎`_dl_find_object`, ‎`epoll_pwait2`, ‎`posix_spawn_file_actions_addtcsetpgrp_np`, ‎`posix_spawnattr_tcgetpgrp_np`, and ‎`posix_spawnattr_tcsetpgrp_np`.
      Show
      .Improved Exception Handling Performance in ‎`glibc` Previously, exception handling in large applications was slow, which impacted performance, particularly in environments with a high volume of users or frequent exceptions. This was due to the time spent in the ‎`__dl_iterate_phdr` function, called from ‎`_Unwind_Find_FDE`. With this update, the exception handling algorithm in `glibc` has been improved to enhance exception processing speed. The update introduces new symbols to the ABI as part of GLIBC_2.35, including ‎`__epoll_pwait2_time64`, ‎`__memcmpeq`, ‎`_dl_find_object`, ‎`epoll_pwait2`, ‎`posix_spawn_file_actions_addtcsetpgrp_np`, ‎`posix_spawnattr_tcgetpgrp_np`, and ‎`posix_spawnattr_tcsetpgrp_np`.
    • Done
    • Required
    • Unspecified
    • Done
    • x86_64, ppc64le
    • Linux
    • None

      We see slow performance in our DB application in situations where many exceptions have to be handled. It happens e.g. on large systems, many users, same query executed by many users. Profiling shows that a lot of time is spent in __dl_iterate_phdr called from _Unwind_Find_FDE.

       

      With (1) libgcc can use a faster approach based on dl_find_object, which was first added to glibc 2.35 with (2)

       

      Both are already available in RHEL10 but as we have many customers on RHEL9 we would like to request a backport of those patches to RHEL9

       

      1- https://gcc.gnu.org/cgit/gcc/diff/libgcc/unwind-dw2-fde-dip.c?id=790854ea7670f1

      2- https://sourceware.org/git/?p=glibc.git;a=commit;h=5d28a8962dcb6ec056b81d730e3c6fb57185a210

              skolosov@redhat.com Sergey Kolosov
              sap-linuxlab-dyordanov Dimitar Yordanov (Inactive)
              DJ Delorie, Frederic Berat
              SAP Confidential Group
              Platform Tools - Libraries Bot Platform Tools - Libraries Bot
              Sergey Kolosov Sergey Kolosov
              Malhar Jivrajani Malhar Jivrajani
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                Created:
                Updated: