[PATCH] firmware: speed up request_firmware()

[Ira Snyder]

Trying to load a large file with request_firmware() is currently very slow,
due to calling vmalloc() for each write. This patch makes the allocations
double in size each time.

Without this patch, loading a 12MB firmware image (FPGA bitfiles) called
vmalloc() approximately 3000 times. With the patch, vmalloc() is only
called 13 times, however, some memory is wasted until firmware_release() is
called. Usually, this happens very quickly, so it shouldn't be a problem.

Without this patch, it took about 2 1/2 minutes to load the 12MB firmware
image. With the patch, it now takes about 1/2 second.

Signed-off-by: Ira W. Snyder <iws@xxxxxxxxxxxxxxxx>
---
 drivers/base/firmware_class.c |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)

diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
index b7e5710..a947a88 100644
--- a/drivers/base/firmware_class.c
+++ b/drivers/base/firmware_class.c
@@ -207,7 +207,12 @@ fw_realloc_buffer(struct firmware_priv *fw_priv, int min_size)
 	if (min_size <= fw_priv->alloc_size)
 		return 0;
 
-	new_size = ALIGN(min_size, PAGE_SIZE);
+	/* Allocate double the current size. If that is not enough, allocate
+	 * the minimum amount needed instead (aligned to PAGE_SIZE). */
+	new_size = fw_priv->alloc_size * 2;
+	if (new_size < min_size)
+		new_size = ALIGN(min_size, PAGE_SIZE);
+
 	new_data = vmalloc(new_size);
 	if (!new_data) {
 		printk(KERN_ERR "%s: unable to alloc buffer\n", __func__);
-- 
1.5.4.3

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