linux-kernel - Re: [PATCH 0/2] Add BLK_FEAT_READ_SYNCHRONOUS and SWP_READ_SYNCHRONOUS

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Message-ID: <17b30f253172cce94d1e2ec86d00e82eea077bde.camel@mediatek.com>
Date: Fri, 11 Oct 2024 09:08:10 +0000
From: Qun-wei Lin (林群崴) <Qun-wei.Lin@...iatek.com>
To: "ying.huang@...el.com" <ying.huang@...el.com>
CC: Andrew Yang (楊智強) <Andrew.Yang@...iatek.com>,
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Subject: Re: [PATCH 0/2] Add BLK_FEAT_READ_SYNCHRONOUS and
 SWP_READ_SYNCHRONOUS_IO

Hi Ying,

Thank you for your question.

The primary motivation for these new feature flags is to handle
scenarios where we want read operations to be completed within the
submit context, while write operations are handled in a different
context.

This does not necessarily imply that the write operations are slow;
rather, it is about optimizing the handling of read and write
operations based on their specific characteristics and requirements.

Best Regards,
Qun-Wei

On Wed, 2024-09-25 at 15:34 +0800, Huang, Ying wrote:
>  	 
> External email : Please do not click links or open attachments until
> you have verified the sender or the content.
>  Qun-Wei Lin <qun-wei.lin@...iatek.com> writes:
> 
> > This patchset introduces 2 new feature flags,
> BLK_FEAT_READ_SYNCHRONOUS and
> > SWP_READ_SYNCHRONOUS_IO.
> >
> > These changes are motivated by the need to better accommodate
> certain swap
> > devices that support synchronous read operations but asynchronous
> write
> > operations.
> >
> > The existing BLK_FEAT_SYNCHRONOUS and SWP_SYNCHRONOUS_IO flags are
> not
> > sufficient for these devices, as they enforce synchronous behavior
> for both
> > read and write operations.
> 
> Which kind of device needs this?  Read fast, but write slow?
> 
> --
> Best Regards,
> Huang, Ying