From e65cec5e5d97927d22b39167d3e8edeffc771788 Mon Sep 17 00:00:00 2001 From: Yury Kotov Date: Mon, 25 Nov 2019 16:36:32 +0300 Subject: migration/ram: Yield periodically to the main loop Usually, incoming migration coroutine yields to the main loop while its IO-channel is waiting for data to receive. But there is a case when RAM migration and data receive have the same speed: VM with huge zeroed RAM. In this case, IO-channel won't read and thus the main loop is stuck and for instance, it doesn't respond to QMP commands. For this case, yield periodically, but not too often, so as not to affect the speed of migration. Signed-off-by: Yury Kotov Reviewed-by: Juan Quintela Signed-off-by: Juan Quintela --- migration/ram.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) (limited to 'migration') diff --git a/migration/ram.c b/migration/ram.c index 1ec5c10561..5cd066467c 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -4246,7 +4246,7 @@ static void colo_flush_ram_cache(void) */ static int ram_load_precopy(QEMUFile *f) { - int flags = 0, ret = 0, invalid_flags = 0, len = 0; + int flags = 0, ret = 0, invalid_flags = 0, len = 0, i = 0; /* ADVISE is earlier, it shows the source has the postcopy capability on */ bool postcopy_advised = postcopy_is_advised(); if (!migrate_use_compression()) { @@ -4258,6 +4258,17 @@ static int ram_load_precopy(QEMUFile *f) void *host = NULL; uint8_t ch; + /* + * Yield periodically to let main loop run, but an iteration of + * the main loop is expensive, so do it each some iterations + */ + if ((i & 32767) == 0 && qemu_in_coroutine()) { + aio_co_schedule(qemu_get_current_aio_context(), + qemu_coroutine_self()); + qemu_coroutine_yield(); + } + i++; + addr = qemu_get_be64(f); flags = addr & ~TARGET_PAGE_MASK; addr &= TARGET_PAGE_MASK; -- cgit v1.2.3