Messages in this thread | | | Date | Fri, 26 Oct 2012 14:58:55 +0800 | From | Fengguang Wu <> | Subject | Re: [PATCH] mm: readahead: remove redundant ra_pages in file_ra_state |
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> 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.
Thanks, Fengguang
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