Tarantool development patches archive
 help / color / mirror / Atom feed
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.

  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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20190226123456.k66j25qv57vygm6u@esperanza \
    --to=vdavydov.dev@gmail.com \
    --cc=georgy@tarantool.org \
    --cc=gorcunov@gmail.com \
    --cc=tarantool-patches@freelists.org \
    --subject='Re: [RFC v3] fiber: Increase default stack size' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox