From: Konstantin Osipov <kostja@tarantool.org> To: tarantool-patches@freelists.org Cc: gorcunov@gmail.com, vdavydov.dev@gmail.com Subject: Re: [tarantool-patches] [rfc 3/4] core/fiber: Put static watermark into stack to track its usage Date: Tue, 5 Mar 2019 11:20:29 +0300 [thread overview] Message-ID: <20190305082029.GL21955@chai> (raw) In-Reply-To: <20190302130034.050488016@gmail.com> * Cyrill Gorcunov <gorcunov@gmail.com> [19/03/03 23:25]: > We want to detect a situation where task in fiber is too eager for > stack and close to its exhausting. For this sake upon stack creation > we put 8 marks on last stack page with step of 128 bytes. Such params > allows us to fill ~1/4 of a page, which does seem reasonable but > we might change this params with time. > > Since the watermark position is permanent and some task is close > to stack limit we print about the situation once to not spam > a user much and stop putting the mark on recycling. > > Closes #3418 As a policy we write meaningful comments for every function, static or not, obvious or not. The idea of such a comment is to reflect the author's intent and technical trade-offs considered when designing a function. The comment should preferably be concise, however. > +/* > + * Random values generated with uuid. > + * Try to fit a cache line. I don't understand this comment. Since you're putting a poison-gap between each number, how could you possibly fit a cache line? > + */ > +static const uint64_t poison_pool[] = { > + 0x74f31d37285c4c37, 0xb10269a05bf10c29, > + 0x0994d845bd284e0f, 0x9ffd4f7129c184df, > + 0x357151e6711c4415, 0x8c5e5f41aafe6f28, > + 0x6917dd79e78049d5, 0xba61957c65ca2465, > +}; > + > +/* > + * We poison by 8 bytes as it natural for stack > + * step on x86-64. Also 128 byte gap between > + * poison values should cover a common cases. > + /** Stack watermark addr for overflow detection. */ > + void *stack_wmark_ofl; Generally we try to avoid abbreviations unless really necessary. Why not simply stack_overflow_watermark? > /** Coro stack size. */ > size_t stack_size; > /** Valgrind stack id. */ -- Konstantin Osipov, Moscow, Russia, +7 903 626 22 32 http://tarantool.io - www.twitter.com/kostja_osipov
next prev parent reply other threads:[~2019-03-05 8:20 UTC|newest] Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-03-02 12:55 [rfc 0/4] fiber/stack: Increase stack size and shrink rss usage Cyrill Gorcunov 2019-03-02 12:55 ` [rfc 1/4] core/fiber: Increase default stack size Cyrill Gorcunov 2019-03-02 12:55 ` [rfc 2/4] core/fiber: Mark stack as unneeded on creation Cyrill Gorcunov 2019-03-02 12:55 ` [rfc 3/4] core/fiber: Put static watermark into stack to track its usage Cyrill Gorcunov 2019-03-05 8:08 ` [tarantool-patches] " Konstantin Osipov 2019-03-05 8:17 ` Cyrill Gorcunov 2019-03-05 8:10 ` Konstantin Osipov 2019-03-05 8:14 ` Cyrill Gorcunov 2019-03-05 19:17 ` Cyrill Gorcunov 2019-03-05 8:20 ` Konstantin Osipov [this message] 2019-03-05 8:27 ` Cyrill Gorcunov 2019-03-02 12:55 ` [rfc 4/4] core/fiber: Shrink stack when recycling Cyrill Gorcunov 2019-03-05 8:30 ` [tarantool-patches] " Konstantin Osipov 2019-03-05 8:41 ` Cyrill Gorcunov 2019-03-05 9:32 ` [tarantool-patches] " Konstantin Osipov
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