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Re: [Qemu-devel] [PATCH v4 1/6] block: use 1 MB bounce buffers for crypt
From: |
Max Reitz |
Subject: |
Re: [Qemu-devel] [PATCH v4 1/6] block: use 1 MB bounce buffers for crypto instead of 16KB |
Date: |
Wed, 27 Sep 2017 22:39:36 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.3.0 |
On 2017-09-27 14:53, Daniel P. Berrange wrote:
> Using 16KB bounce buffers creates a significant performance
> penalty for I/O to encrypted volumes on storage which high
> I/O latency (rotating rust & network drives), because it
> triggers lots of fairly small I/O operations.
>
> On tests with rotating rust, and cache=none|directsync,
> write speed increased from 2MiB/s to 32MiB/s, on a par
> with that achieved by the in-kernel luks driver. With
> other cache modes the in-kernel driver is still notably
> faster because it is able to report completion of the
> I/O request before any encryption is done, while the
> in-QEMU driver must encrypt the data before completion.
>
> Signed-off-by: Daniel P. Berrange <address@hidden>
> ---
> block/crypto.c | 28 +++++++++++++++-------------
> 1 file changed, 15 insertions(+), 13 deletions(-)
Reviewed-by: Max Reitz <address@hidden>
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- [Qemu-devel] [PATCH v4 0/6] Misc improvements to crypto block driver, Daniel P. Berrange, 2017/09/27
- [Qemu-devel] [PATCH v4 1/6] block: use 1 MB bounce buffers for crypto instead of 16KB, Daniel P. Berrange, 2017/09/27
- [Qemu-devel] [PATCH v4 2/6] crypto: expose encryption sector size in APIs, Daniel P. Berrange, 2017/09/27
- [Qemu-devel] [PATCH v4 3/6] block: fix data type casting for crypto payload offset, Daniel P. Berrange, 2017/09/27
- [Qemu-devel] [PATCH v4 6/6] block: support passthrough of BDRV_REQ_FUA in crypto driver, Daniel P. Berrange, 2017/09/27
- [Qemu-devel] [PATCH v4 5/6] block: convert qcrypto_block_encrypt|decrypt to take bytes offset, Daniel P. Berrange, 2017/09/27
- [Qemu-devel] [PATCH v4 4/6] block: convert crypto driver to bdrv_co_preadv|pwritev, Daniel P. Berrange, 2017/09/27
- Re: [Qemu-devel] [PATCH v4 0/6] Misc improvements to crypto block driver, Max Reitz, 2017/09/27