linux-kernel - [PATCH 0/2] add block size > page size support to ramfs

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Message-ID: <20240924192351.74728-1-kernel@pankajraghav.com>
Date: Tue, 24 Sep 2024 21:23:49 +0200
From: "Pankaj Raghav (Samsung)" <kernel@...kajraghav.com>
To: linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: willy@...radead.org,
	mcgrof@...nel.org,
	gost.dev@...sung.com,
	akpm@...ux-foundation.org,
	kernel@...kajraghav.com,
	Christian Brauner <brauner@...nel.org>,
	Pankaj Raghav <p.raghav@...sung.com>
Subject: [PATCH 0/2] add block size > page size support to ramfs

From: Pankaj Raghav <p.raghav@...sung.com>

Add block size > page size to ramfs as we support minimum folio order
allocation in the page cache. The changes are very minimal, and this is
also a nice way to stress test just the page cache changes for minimum
folio order.

I tested the changes from blocksize 4k to 2M with ltp's fsx on an x86
machine.

I ran a basic perf test with dd as follows:
$ mount ramfs -t ramfs -o blocksize=$bs /media/test/
$ dd if=/mnt/rand of="/media/test/rand" bs=2M count=2048

+------+----------+
|  bs  | BW(GB/s) |
+------+----------+
| 4k   |      1.7 |
| 8k   |      2.4 |
| 16k  |      3.2 |
| 32k  |      4.0 |
| 64k  |      4.5 |
| 128k |      4.8 |
| 256k |      5.3 |
| 512k |      5.5 |
| 1M   |      5.6 |
| 2M   |      5.6 |
+------+----------+

We get better performance for larger bs as we allocate larger folios
instead of multiple smaller folios when there is no memory fragmentation
and pressure.

Pankaj Raghav (2):
  ramfs: add blocksize mount option
  ramfs: enable block size > page size

 fs/ramfs/inode.c | 27 +++++++++++++++++++++++++--
 1 file changed, 25 insertions(+), 2 deletions(-)


base-commit: 4d0326b60bb753627437fff0f76bf1525bcda422
-- 
2.44.1