linux-kernel - Re: [PATCH 0/3] readfile(2): a new syscall to make open/read/close faster

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Date:   Sun, 5 Jul 2020 04:06:22 +0200
From:   Jan Ziak <0xe2.0x9a.0x9b@...il.com>
To:     gregkh@...uxfoundation.org
Cc:     linux-api@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org,
        linux-man@...r.kernel.org, mtk.manpages@...il.com,
        shuah@...nel.org, viro@...iv.linux.org.uk
Subject: Re: [PATCH 0/3] readfile(2): a new syscall to make open/read/close faster

Hello

At first, I thought that the proposed system call is capable of
reading *multiple* small files using a single system call - which
would help increase HDD/SSD queue utilization and increase IOPS (I/O
operations per second) - but that isn't the case and the proposed
system call can read just a single file.

Without the ability to read multiple small files using a single system
call, it is impossible to increase IOPS (unless an application is
using multiple reader threads or somehow instructs the kernel to
prefetch multiple files into memory).

While you are at it, why not also add a readfiles system call to read
multiple, presumably small, files? The initial unoptimized
implementation of readfiles syscall can simply call readfile
sequentially.

Sincerely
Jan (atomsymbol)