From: Cai Huoqing <caihuoqing@baidu.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: Michael Cyr <mikecyr@linux.ibm.com>,
"James E.J. Bottomley" <jejb@linux.ibm.com>,
"Martin K. Petersen" <martin.petersen@oracle.com>,
<linux-scsi@vger.kernel.org>, <target-devel@vger.kernel.org>,
<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] scsi: ibmvscsi_tgt: Use dma_alloc_coherent() instead of get_zeroed_page/dma_map_single()
Date: Mon, 11 Oct 2021 15:04:05 +0800 [thread overview]
Message-ID: <20211011070405.GA173@LAPTOP-UKSR4ENP.internal.baidu.com> (raw)
In-Reply-To: <YWPc1GxFiOloHveI@infradead.org>
On 11 10月 21 07:42:28, Christoph Hellwig wrote:
> On Mon, Oct 11, 2021 at 12:00:53AM +0800, Cai Huoqing wrote:
> > Replacing get_zeroed_page/free_page/dma_map_single/dma_unmap_single()
> > with dma_alloc_coherent/dma_free_coherent() helps to reduce
> > code size, and simplify the code, and coherent DMA will not
> > clear the cache every time.
>
> This explanation does not make any sense whatsoever. Please explain
> why it would an show numbers.
Hi Christoph,
thanks for your feedback.
In this case, just simplify the code.
10 insertions(+), 31 deletions(-)
dma_sync_ API is not called, I think the hardware may keep cache coherent
directly or is a no cache system. No need to make perfermance compare.
thanks
Cai
next prev parent reply other threads:[~2021-10-11 7:04 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-10 16:00 Cai Huoqing
2021-10-11 6:42 ` Christoph Hellwig
2021-10-11 7:04 ` Cai Huoqing [this message]
2021-10-11 7:26 ` Christoph Hellwig
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