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Re: [RFC] Offloading Support in libgomp
- From: "Michael V. Zolotukhin" <michael dot v dot zolotukhin at gmail dot com>
- To: Jakub Jelinek <jakub at redhat dot com>
- Cc: Marek Polacek <polacek at redhat dot com>, Kirill Yukhin <kirill dot yukhin at gmail dot com>, Richard Henderson <rth at redhat dot com>, gcc-patches at gcc dot gnu dot org, triegel at redhat dot com
- Date: Sun, 15 Sep 2013 19:41:24 +0400
- Subject: Re: [RFC] Offloading Support in libgomp
- Authentication-results: sourceware.org; auth=none
- References: <20130910153624 dot GD1817 at tucnak dot redhat dot com> <20130910153810 dot GC2059 at msticlxl57 dot ims dot intel dot com> <20130913112930 dot GC30181 at msticlxl57 dot ims dot intel dot com> <20130913123614 dot GB1817 at tucnak dot redhat dot com> <20130913131109 dot GD30181 at msticlxl57 dot ims dot intel dot com> <20130913131556 dot GD1817 at tucnak dot redhat dot com> <20130913153527 dot GH1817 at tucnak dot redhat dot com> <20130913154103 dot GT23899 at redhat dot com> <20130914192956 dot GI1817 at tucnak dot redhat dot com> <20130915093007 dot GA60139 at msticlxl57 dot ims dot intel dot com>
> Libgomp will start N-1 new threads, and all of them would want to look up
> mappings for i1,i2,...iK in the splay tree. The first one wouldn't find
> anything and would map and insert all the values to the tree. But the following
> ones would look-up these addresses in the exactly same order, which will lead to
> totally unbalanced tree.
>
> Am I missing anything or is it a real problem?
On second thought, this access order doesn't necessarily mean accessing in
ascending/descending keys order, so there is no problem here.
Thanks, Michael