[linuxppc-release] [PATCH v2 4/4] fsl-dma: use spin_lock_bh to instead of spin_lock_irqsave

[Liu Qiang-B32616]

> -----Original Message-----
> From: Tabi Timur-B04825
> Sent: Wednesday, July 11, 2012 11:01 PM
> To: Liu Qiang-B32616
> Cc: linux-crypto at vger.kernel.org; linuxppc-dev at lists.ozlabs.org; Vinod
> Koul; herbert at gondor.hengli.com.au; Dan Williams; Li Yang-R58472;
> davem at davemloft.net
> Subject: Re: [linuxppc-release] [PATCH v2 4/4] fsl-dma: use spin_lock_bh
> to instead of spin_lock_irqsave
> 
> Qiang Liu wrote:
> > Use spin_lock_bh to instead of spin_lock_irqsave for improving
> performance.
> 
> Please provide some evidence that performance has improved, as well as an
> explanation why it's okay to use spin_lock_bh, and why it's faster.
I compared my test result before and after this patch, write performance can
improved by 15%. I will send the latest patches sooner because of Ira's concern.
I will give a complete description about the improvement of spin_lock_bh().

About your question, spin_lock_bh is used in the case of bottom/half as its
name, there is no need to protect a running/pending list with spin_lock_irqsave.

Thanks.

> --
> Timur Tabi
> Linux kernel developer at Freescale