| Date | Sat, 27 May 2006 14:38:26 +0800 | From | Wu Fengguang <> | Subject | Re: [PATCH 20/33] readahead: initial method - expected read size |
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On Fri, May 26, 2006 at 10:29:34AM -0700, Andrew Morton wrote: > Wu Fengguang <wfg@mail.ustc.edu.cn> wrote: > > > > backing_dev_info.ra_expect_bytes is dynamicly updated to be the expected > > read pages on start-of-file. It allows the initial readahead to be more > > aggressive and hence efficient. > > > > > > +void fastcall readahead_close(struct file *file) > > eww, fastcall.
Hehe, it's a tiny function, and calls no further sub-routines except debugging ones. Still not necessary?
> > +{ > > + struct inode *inode = file->f_dentry->d_inode; > > + struct address_space *mapping = inode->i_mapping; > > + struct backing_dev_info *bdi = mapping->backing_dev_info; > > + unsigned long pos = file->f_pos; > > f_pos is loff_t.
Just meant to be a little more compact ;)
+ unsigned long pos = file->f_pos; + unsigned long pgrahit = file->f_ra.cache_hits; + unsigned long pgaccess = 1 + pos / PAGE_CACHE_SIZE; + unsigned long pgcached = mapping->nrpages; + + if (!pos) /* pread */ + return; + + if (pgcached > bdi->ra_pages0) /* excessive reads */ + return;
Here the f_pos will almost definitely has small values.
+ + if (pgaccess >= pgcached) {
Fixed by adding a comment to clarify it:
+ unsigned long pos = file->f_pos; /* supposed to be small */ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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