LKML Archive on
help / color / mirror / Atom feed
From: David Miller <>
Subject: Re: Size of 2.6.20 task_struct on x86_64 machines
Date: Thu, 08 Feb 2007 12:19:45 -0800 (PST)	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

From: William Cohen <>
Date: Thu, 08 Feb 2007 11:14:13 -0500

> This past week I was playing around with that pahole tool
> ( and looking at the
> size of various struct in the kernel. I was surprised by the size of
> the task_struct on x86_64, approaching 4K.  I looked through the
> fields in task_struct and found that a number of them were declared as
> "unsigned long" rather than "unsigned int" despite them appearing okay
> as 32-bit sized fields. On x86_64 "unsigned long" ends up being 8
> bytes in size and forces 8 byte alignment. Is there a reason there
> a reason they are "unsigned long"?

I think at one point we used the atomic bit operations to operate on
things like tsk->flags, and those interfaces require unsigned long as
the type.

That doesn't appear to be the case any longer, so at a minimum
your tsk->flags conversion to unsigned int should be ok.

  reply	other threads:[~2007-02-08 20:19 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-02-08 16:14 William Cohen
2007-02-08 20:19 ` David Miller [this message]
2007-02-08 21:03   ` Andrew Morton
2007-02-11  0:20 ` Dave Jones
2007-02-11  2:55   ` Linus Torvalds

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:

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

  git send-email \ \ \ \ \
    --subject='Re: Size of 2.6.20 task_struct on x86_64 machines' \

* 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;
as well as URLs for NNTP newsgroup(s).