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Re: [PATCH 0/7] Disable lazy tlsdesc on aarch64 and arm
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: Szabolcs Nagy <szabolcs dot nagy at arm dot com>
- Cc: GNU C Library <libc-alpha at sourceware dot org>, nd <nd at arm dot com>
- Date: Tue, 24 Oct 2017 07:54:00 -0700
- Subject: Re: [PATCH 0/7] Disable lazy tlsdesc on aarch64 and arm
- Authentication-results: sourceware.org; auth=none
- References: <59EF4CEC.8020301@arm.com>
On Tue, Oct 24, 2017 at 7:23 AM, Szabolcs Nagy <szabolcs.nagy@arm.com> wrote:
> Reorganized the aarch64 patches a bit and added patches for arm too.
>
> The reason behind this change is the data race BZ #18034 on aarch64
> and equivalent BZ #18572 on arm. The aarch64 bug was fixed by adding
> synchronization but that causes significant performance regression
> of tls access. Lazy initialization of tlsdesc was never justified,
> so i'm proposing to remove it on weakly ordered memory architectures.
> (For consistency i think it should be removed on x86 too, but i don't
> have patches for that.)
>
> Szabolcs Nagy (7):
> Mark lazy tlsdesc helper functions unused to avoid warnings
> aarch64: Disable lazy symbol binding of TLSDESC
> aarch64: Remove barriers from TLS descriptor functions
> [BZ #17078] arm: remove prelinker support for R_ARM_TLS_DESC
> [BZ #18572] arm: Disable lazy initialization of tlsdesc entries
> arm: Remove unnecessary volatile qualifier
> arm: Remove lazy tlsdesc initialization related code
>
>
TLSDESC is very rarely used/tested. Should we remove lazy binding
TLSDESC for all targets? It will simplify TLSDESC code.
--
H.J.