Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Wed, 23 Mar 2022 08:16:41 +0100
From:   Greg KH <gregkh@linuxfoundation.org>
To:     Miklos Szeredi <mszeredi@redhat.com>
Cc:     linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-api@vger.kernel.org, linux-man@vger.kernel.org,
        linux-security-module@vger.kernel.org, Karel Zak <kzak@redhat.com>,
        Ian Kent <raven@themaw.net>,
        David Howells <dhowells@redhat.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Christian Brauner <christian@brauner.io>,
        Amir Goldstein <amir73il@gmail.com>,
        James Bottomley <James.Bottomley@hansenpartnership.com>
Subject: Re: [RFC PATCH] getvalues(2) prototype
Message-ID: <YjrJWf+XMnWVd6K0@kroah.com>
References: <20220322192712.709170-1-mszeredi@redhat.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20220322192712.709170-1-mszeredi@redhat.com>
Precedence: bulk

On Tue, Mar 22, 2022 at 08:27:12PM +0100, Miklos Szeredi wrote:
> Add a new userspace API that allows getting multiple short values in a
> single syscall.
> 
> This would be useful for the following reasons:
> 
> - Calling open/read/close for many small files is inefficient.  E.g. on my
>   desktop invoking lsof(1) results in ~60k open + read + close calls under
>   /proc and 90% of those are 128 bytes or less.

As I found out in testing readfile():
	https://lore.kernel.org/r/20200704140250.423345-1-gregkh@linuxfoundation.org

microbenchmarks do show a tiny improvement in doing something like this,
but that's not a real-world application.

Do you have anything real that can use this that shows a speedup?

thanks,

greg k-h