On Wed, 12 Jan 2000, Ananth Ananthanarayanan wrote:
>I'm trying to measure the performance of ext2 read
>when the read has to actually hit the device.
>I've set up a little system call, which takes
>the fd and invalidates the pages associated with
>that fd from the buffer/page cache. Basically,
>the system call does:
>
> filp = fget(fd);
> invalidate_inode_pages(filp->f_dentry->d_inode);
>
>The above seems to do the right thing in that
>a read on that fd goes to the disk. But, the
>amount of free memory goes down drastically,
>as reported by vmstat ... in fact after a few
>runs of the test, the system starts swapping.
Because the page gets not really freed if it had buffers queued on it.
invalidate_inode_pages only has to be called by filesystems that can't
generate dirty data and so that can't overlap buffer on the page cache.
Andrea
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This archive was generated by hypermail 2b29 : Sat Jan 15 2000 - 21:00:21 EST