From 44815334e10365ae5c60914c1d9fcecfe5ed5982 Mon Sep 17 00:00:00 2001 From: Peter Lieven Date: Thu, 8 Mar 2018 12:18:27 +0100 Subject: migration/block: limit the number of parallel I/O requests the current implementation submits up to 512 I/O requests in parallel which is much to high especially for a background task. This patch adds a maximum limit of 16 I/O requests that can be submitted in parallel to avoid monopolizing the I/O device. Signed-off-by: Peter Lieven Message-Id: <1520507908-16743-5-git-send-email-pl@kamp.de> Reviewed-by: Juan Quintela Signed-off-by: Dr. David Alan Gilbert --- migration/block.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/migration/block.c b/migration/block.c index 5c03632257..03bbba61cb 100644 --- a/migration/block.c +++ b/migration/block.c @@ -37,6 +37,7 @@ #define MAX_IS_ALLOCATED_SEARCH (65536 * BDRV_SECTOR_SIZE) #define MAX_IO_BUFFERS 512 +#define MAX_PARALLEL_IO 16 //#define DEBUG_BLK_MIGRATION @@ -775,6 +776,7 @@ static int block_save_iterate(QEMUFile *f, void *opaque) while ((block_mig_state.submitted + block_mig_state.read_done) * BLOCK_SIZE < qemu_file_get_rate_limit(f) && + block_mig_state.submitted < MAX_PARALLEL_IO && (block_mig_state.submitted + block_mig_state.read_done) < MAX_IO_BUFFERS) { blk_mig_unlock(); -- cgit v1.2.3