Tarantool development patches archive
 help / color / mirror / Atom feed
From: Vladimir Davydov <vdavydov.dev@gmail.com>
To: Konstantin Osipov <kostja@tarantool.org>
Cc: tarantool-patches@freelists.org
Subject: Re: [PATCH 1/2] xlog: use ev_sleep instead of fiber_sleep for rate limiting
Date: Mon, 4 Jun 2018 12:51:33 +0300	[thread overview]
Message-ID: <20180604095133.iaxtdven3kjpuff5@esperanza> (raw)
In-Reply-To: <20180601175255.GA15567@atlas>

On Fri, Jun 01, 2018 at 08:52:55PM +0300, Konstantin Osipov wrote:
> * Vladimir Davydov <vdavydov.dev@gmail.com> [18/05/29 18:20]:
> > fiber_sleep() works only if the current thread was created with
> > cord_costart(). Since vinyl worker threads don't need fibers, they
> > are created with cord_start() and hence can't use fiber_sleep().
> > So to be able to limit rate of vinyl dump/compaction, we have to
> > use ev_sleep() instead of fiber_sleep() in xlog. This is fine by
> > other xlog writers, because they don't use fibers either, neither
> > they should as xlogs are written without coio.
> > 
> > Needed for #3220
> 
> Please use cord_costart() in vinyl workers instead.

For this to work, we would need to yield periodically (fiber_sleep(0))
while writing a run file. This would look weird as each worker thread
executes just one task.

Anyway, yielding in xlog_write() may be unexpected from caller's pov,
because this function is blocking (writes a file) and isn't supposed
to yield. One usually hands it over to coio or a worker thread, where
yielding is pointless.

> 
> We will end up needing it for other things and it's nearly free.

What things?

  reply	other threads:[~2018-06-04  9:51 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-29 15:19 [PATCH 0/2] vinyl: allow to limit dump bandwidth Vladimir Davydov
2018-05-29 15:19 ` [PATCH 1/2] xlog: use ev_sleep instead of fiber_sleep for rate limiting Vladimir Davydov
2018-06-01 17:52   ` Konstantin Osipov
2018-06-04  9:51     ` Vladimir Davydov [this message]
2018-06-07 13:11       ` Konstantin Osipov
2018-05-29 15:19 ` [PATCH 2/2] vinyl: apply box.cfg.snap_io_rate_limit to dump/compaction Vladimir Davydov
2018-06-01 17:56   ` Konstantin Osipov
2018-06-04  9:55     ` Vladimir Davydov

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=20180604095133.iaxtdven3kjpuff5@esperanza \
    --to=vdavydov.dev@gmail.com \
    --cc=kostja@tarantool.org \
    --cc=tarantool-patches@freelists.org \
    --subject='Re: [PATCH 1/2] xlog: use ev_sleep instead of fiber_sleep for rate limiting' \
    /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