From: Vladimir Davydov <vdavydov.dev@gmail.com> To: Cyrill Gorcunov <gorcunov@gmail.com> Cc: "Георгий Кириченко" <georgy@tarantool.org>, tarantool-patches@freelists.org Subject: Re: [RFC v3] fiber: Increase default stack size Date: Tue, 26 Feb 2019 15:34:56 +0300 [thread overview] Message-ID: <20190226123456.k66j25qv57vygm6u@esperanza> (raw) In-Reply-To: <20190226111632.GM7198@uranus> On Tue, Feb 26, 2019 at 02:16:32PM +0300, Cyrill Gorcunov wrote: > > - 1 MB for max stack size seems to be a bit of an overkill for now. > > The default value should be set to 256 KB, but we do need a > > configuration option for it. Let's add it to the fiber Lua module. > > May be done in a separate patch, but should be submitted together in > > the same patch set. > > Wait, first fiber for main cord is created before lua init, isn't it? > I already though about using lua config for it but fiber init'ed at > very early stage. Yeah, good point, I haven't thought about it. Then we have to either always allocate a big stack for the main fiber or use an environment variable. Let's get back to it later and first make the stack size limit statically defined. > > > - 16 byte unique identifier for detecting stack overflow doesn't seem > > to be enough. Imagine a PATH_MAX buffer allocated on stack that uses > > only a hundred bytes for path formatting. It can easily jump over the > > watermark. We should probably use random poisoning: say, 4 unique > > identifiers 8 bytes each scattered a few hundred bytes apart. Some > > math/reasoning behind this would be nice to see in the comments. > > If we want to scatter we should simply put marks at page bounds. > Dirtifying somewhere inside middle of a page is useless. Hmm, why? Consider the example with PATH_MAX buffer. Putting dirty marks at page boundaries doesn't guarantee any of them will get overwritten by the buffer if only a few hundred of bytes are used. I think we should dirty the last page or two at random intervals - this should increase the chance that at least one mark is overwritten by any function that is eager for the stack.
next prev parent reply other threads:[~2019-02-26 12:34 UTC|newest] Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-02-22 20:16 [tarantool-patches] [RFC v2] " Cyrill Gorcunov 2019-02-25 14:55 ` Vladimir Davydov 2019-02-25 15:25 ` Cyrill Gorcunov 2019-02-25 21:39 ` [RFC v3] " Cyrill Gorcunov 2019-02-26 8:58 ` Vladimir Davydov 2019-02-26 9:12 ` Cyrill Gorcunov 2019-02-26 10:26 ` Vladimir Davydov 2019-02-26 10:36 ` Vladimir Davydov 2019-02-26 11:17 ` Cyrill Gorcunov 2019-02-26 12:25 ` Vladimir Davydov 2019-02-26 11:16 ` Cyrill Gorcunov 2019-02-26 12:34 ` Vladimir Davydov [this message] 2019-02-26 12:54 ` Cyrill Gorcunov 2019-02-26 13:06 ` Vladimir Davydov 2019-02-26 13:26 ` [tarantool-patches] " Konstantin Osipov 2019-02-26 14:02 ` Cyrill Gorcunov 2019-02-26 10:32 ` Vladimir Davydov 2019-02-26 11:18 ` Cyrill Gorcunov
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