Messages in this thread | | | Date | Fri, 26 Oct 2012 15:03:12 +0800 | From | Ni zhan Chen <> | Subject | Re: [PATCH] mm: readahead: remove redundant ra_pages in file_ra_state |
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On 10/26/2012 02:58 PM, Fengguang Wu wrote: >> static void shrink_readahead_size_eio(struct file *filp, >> struct file_ra_state *ra) >> { >> - ra->ra_pages /= 4; >> + spin_lock(&filp->f_lock); >> + filp->f_mode |= FMODE_RANDOM; >> + spin_unlock(&filp->f_lock); >> >> As the example in comment above this function, the read maybe still >> sequential, and it will waste IO bandwith if modify to FMODE_RANDOM >> directly. > Yes immediately disabling readahead may hurt IO performance, the > original '/ 4' may perform better when there are only 1-3 IO errors > encountered.
Hi Fengguang,
Why the number should be 1-3?
Regards, Chen
> > Thanks, > Fengguang > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@kvack.org. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a> >
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