Attachment 147784 Details for Bug 147679 – Proposed patch

[patch] Proposed patch

dm-striped-readahead.patch (text/plain), 1.35 KB, created by Milan Broz on 2007-02-09 16:05:49 UTC

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Creator: Milan Broz

Created: 2007-02-09 16:05:49 UTC

Size: 1.35 KB

patch

obsolete

>Calculate correct readahead for the striped target
>to avoid read performance degradation.
>
>(using the same strategy like md raid0 driver)
>
>Signed-off-by: Milan Broz <mbroz@redhat.com>
>
>Index: linux-2.6.9/drivers/md/dm-stripe.c
>===================================================================
>--- linux-2.6.9.orig/drivers/md/dm-stripe.c	2007-02-09 16:54:28.000000000 +0100
>+++ linux-2.6.9/drivers/md/dm-stripe.c	2007-02-09 16:55:02.000000000 +0100
>@@ -69,13 +69,15 @@ static int get_stripe(struct dm_target *
>  */
> static int stripe_ctr(struct dm_target *ti, unsigned int argc, char **argv)
> {
>+	struct mapped_device *md = NULL;
>+	struct backing_dev_info *rd_bdi;
> 	struct stripe_c *sc;
> 	sector_t width;
> 	uint32_t stripes;
> 	uint32_t chunk_size;
> 	char *end;
> 	int r;
>-	unsigned int i;
>+	unsigned int i, ra_stripe;
> 
> 	if (argc < 2) {
> 		ti->error = "dm-stripe: Not enough arguments";
>@@ -158,6 +160,20 @@ static int stripe_ctr(struct dm_target *
> 		}
> 	}
> 
>+	/*
>+	 * set read-ahead to 2 * whole stripe
>+	 * (if the devices have greater readahead,
>+	 * user should increase chunksize)
>+	 */
>+	md = dm_table_get_md(ti->table);
>+	rd_bdi = &dm_disk(md)->queue->backing_dev_info;
>+	ra_stripe = sc->stripes * (ti->split_io << SECTOR_SHIFT) / PAGE_SIZE;
>+
>+	if (rd_bdi->ra_pages < 2 * ra_stripe)
>+		rd_bdi->ra_pages = 2 * ra_stripe;
>+
>+	dm_put(md);
>+
> 	ti->private = sc;
> 	return 0;
> }

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Attachments on bug 147679: 147784