From: Eric Biggers <ebiggers@kernel.org>
To: Jeff Lien <jeff.lien@wdc.com>
Cc: linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org,
linux-block@vger.kernel.org, linux-scsi@vger.kernel.org,
herbert@gondor.apana.org.au, tim.c.chen@linux.intel.com,
martin.petersen@oracle.com, david.darrington@wdc.com,
jeff.furlong@wdc.com
Subject: Re: [PATCH] Performance Improvement in CRC16 Calculations.
Date: Fri, 10 Aug 2018 13:16:02 -0700 [thread overview]
Message-ID: <20180810201601.GA80850@gmail.com> (raw)
In-Reply-To: <1533928331-21303-1-git-send-email-jeff.lien@wdc.com>
On Fri, Aug 10, 2018 at 02:12:11PM -0500, Jeff Lien wrote:
> This patch provides a performance improvement for the CRC16 calculations done in read/write
> workloads using the T10 Type 1/2/3 guard field. For example, today with sequential write
> workloads (one thread/CPU of IO) we consume 100% of the CPU because of the CRC16 computation
> bottleneck. Today's block devices are considerably faster, but the CRC16 calculation prevents
> folks from utilizing the throughput of such devices. To speed up this calculation and expose
> the block device throughput, we slice the old single byte for loop into a 16 byte for loop,
> with a larger CRC table to match. The result has shown 5x performance improvements on various
> big endian and little endian systems running the 4.18.0 kernel version.
>
> FIO Sequential Write, 64K Block Size, Queue Depth 64
> BE Base Kernel: bw=201.5 MiB/s
> BE Modified CRC Calc: bw=968.1 MiB/s
> 4.80x performance improvement
>
> LE Base Kernel: bw=357 MiB/s
> LE Modified CRC Calc: bw=1964 MiB/s
> 5.51x performance improvement
>
> FIO Sequential Read, 64K Block Size, Queue Depth 64
> BE Base Kernel: bw=611.2 MiB/s
> BE Modified CRC calc: bw=684.9 MiB/s
> 1.12x performance improvement
>
> LE Base Kernel: bw=797 MiB/s
> LE Modified CRC Calc: bw=2730 MiB/s
> 3.42x performance improvement
Did you also test the slice-by-4 (requires 2048-byte table) and slice-by-8
(requires 4096-byte table) methods? Your proposal is slice-by-16 (requires
8192-byte table); the original was slice-by-1 (requires 512-byte table).
> __u16 crc_t10dif_generic(__u16 crc, const unsigned char *buffer, size_t len)
> {
> - unsigned int i;
> + const __u8 *i = (const __u8 *)buffer;
> + const __u8 *i_end = i + len;
> + const __u8 *i_last16 = i + (len / 16 * 16);
'i' is normally a loop counter, not a pointer.
Use 'p', 'p_end', and 'p_last16'.
>
> - for (i = 0 ; i < len ; i++)
> - crc = (crc << 8) ^ t10_dif_crc_table[((crc >> 8) ^ buffer[i]) & 0xff];
> + for (; i < i_last16; i += 16) {
> + crc = t10_dif_crc_table[15][i[0] ^ (__u8)(crc >> 8)] ^
> + t10_dif_crc_table[14][i[1] ^ (__u8)(crc >> 0)] ^
> + t10_dif_crc_table[13][i[2]] ^
> + t10_dif_crc_table[12][i[3]] ^
> + t10_dif_crc_table[11][i[4]] ^
> + t10_dif_crc_table[10][i[5]] ^
> + t10_dif_crc_table[9][i[6]] ^
> + t10_dif_crc_table[8][i[7]] ^
> + t10_dif_crc_table[7][i[8]] ^
> + t10_dif_crc_table[6][i[9]] ^
> + t10_dif_crc_table[5][i[10]] ^
> + t10_dif_crc_table[4][i[11]] ^
> + t10_dif_crc_table[3][i[12]] ^
> + t10_dif_crc_table[2][i[13]] ^
> + t10_dif_crc_table[1][i[14]] ^
> + t10_dif_crc_table[0][i[15]];
> + }
Please indent this properly.
crc = t10_dif_crc_table[15][i[0] ^ (__u8)(crc >> 8)] ^
t10_dif_crc_table[14][i[1] ^ (__u8)(crc >> 0)] ^
t10_dif_crc_table[13][i[2]] ^
t10_dif_crc_table[12][i[3]] ^
t10_dif_crc_table[11][i[4]] ^
...
- Eric
next prev parent reply other threads:[~2018-08-10 20:16 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-10 19:12 [PATCH] Performance Improvement in CRC16 Calculations Jeff Lien
2018-08-10 19:23 ` Joe Perches
2018-08-10 20:02 ` Nicolas Pitre
2018-08-11 0:11 ` Joe Perches
2018-08-11 0:34 ` Nicolas Pitre
2018-08-11 2:39 ` Douglas Gilbert
2018-08-11 9:04 ` Joe Perches
2018-08-11 15:06 ` Joe Perches
2018-08-13 18:41 ` Jeffrey Lien
2018-08-13 3:36 ` Douglas Gilbert
2018-08-13 4:29 ` Joe Perches
2018-08-10 20:00 ` Nicolas Pitre
2018-08-10 20:16 ` Eric Biggers [this message]
2018-08-16 14:02 ` Jeffrey Lien
2018-08-16 14:22 ` Douglas Gilbert
2018-08-16 15:41 ` Christophe LEROY
2018-08-16 17:38 ` Douglas Gilbert
2018-08-17 3:20 ` Martin K. Petersen
2018-08-16 15:47 ` Christophe LEROY
2018-08-10 20:56 ` Douglas Gilbert
2018-08-11 15:36 ` Martin K. Petersen
2018-08-11 16:35 ` Joe Perches
2018-08-22 1:40 ` Martin K. Petersen
2018-08-22 6:20 ` Christoph Hellwig
2018-08-24 15:32 ` Jeffrey Lien
2018-08-24 15:39 ` Ard Biesheuvel
2018-08-24 16:29 ` Martin K. Petersen
2018-08-24 17:38 ` Ard Biesheuvel
2018-08-24 21:46 ` Martin K. Petersen
2018-08-24 21:54 ` Ard Biesheuvel
2018-08-24 22:12 ` Martin K. Petersen
2018-08-25 6:12 ` Herbert Xu
2018-08-26 2:35 ` Martin K. Petersen
2018-08-26 2:40 ` [PATCH 1/4] crypto: Introduce notifier for new crypto algorithms Martin K. Petersen
2018-08-26 2:40 ` [PATCH 2/4] crc-t10dif: Pick better transform if one becomes available Martin K. Petersen
2018-08-27 6:13 ` Herbert Xu
2018-08-26 2:40 ` [PATCH 3/4] crc-t10dif: Allow current transform to be inspected in sysfs Martin K. Petersen
2018-08-26 2:40 ` [PATCH 4/4] block: Integrity profile init function to trigger module loads Martin K. Petersen
2018-08-26 8:22 ` Ard Biesheuvel
2018-08-26 13:30 ` Martin K. Petersen
2018-08-26 13:44 ` Ard Biesheuvel
2018-08-26 13:48 ` Martin K. Petersen
2018-08-27 6:09 ` [PATCH 1/4] crypto: Introduce notifier for new crypto algorithms Herbert Xu
2018-08-30 14:57 ` Martin K. Petersen
2018-08-30 15:00 ` [PATCH v2 1/3] " Martin K. Petersen
2018-08-30 15:00 ` [PATCH v2 2/3] crc-t10dif: Pick better transform if one becomes available Martin K. Petersen
2018-08-30 15:00 ` [PATCH v2 3/3] crc-t10dif: Allow current transform to be inspected in sysfs Martin K. Petersen
2018-08-31 17:17 ` [PATCH v2 1/3] crypto: Introduce notifier for new crypto algorithms Jeffrey Lien
2018-09-04 5:21 ` Herbert Xu
2018-09-04 13:30 ` Torsten Duwe
2018-08-24 16:30 ` [PATCH] Performance Improvement in CRC16 Calculations Martin K. Petersen
2018-08-13 4:44 ` Chaitanya Kulkarni
2018-08-13 11:45 ` David Laight
2018-08-13 13:50 ` David Laight
2018-08-13 22:44 ` Tim Chen
2018-08-15 12:51 ` Jeffrey Lien
2018-08-15 18:31 ` Pavel Machek
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