Re: [PATCH 2/3] block: add logging facility for long standing IO requests

[Philippe Mathieu-Daudé]

On 8/5/20 12:08 PM, Denis V. Lunev wrote:
> There are severe delays with IO requests processing if QEMU is running in
> virtual machine or over software defined storage. Such delays potentially
> results in unpredictable guest behavior. For example, guests over IDE or
> SATA drive could remount filesystem read-only if write is performed
> longer than 10 seconds.
> 
> Such reports are very complex to process. Some good starting point for this
> seems quite reasonable. This patch provides one. It adds logging of such
> potentially dangerous long IO operations.
> 
> Signed-off-by: Denis V. Lunev <den@openvz.org>
> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> CC: Stefan Hajnoczi <stefanha@redhat.com>
> CC: Kevin Wolf <kwolf@redhat.com>
> CC: Max Reitz <mreitz@redhat.com>
> ---
>  block/accounting.c         | 59 +++++++++++++++++++++++++++++++++++++-
>  blockdev.c                 |  7 ++++-
>  include/block/accounting.h |  5 +++-
>  slirp                      |  2 +-
>  4 files changed, 69 insertions(+), 4 deletions(-)
> 
...

>  typedef struct BlockAcctCookie {
> @@ -101,7 +104,7 @@ typedef struct BlockAcctCookie {
>  
>  void block_acct_init(BlockAcctStats *stats);
>  void block_acct_setup(BlockAcctStats *stats, bool account_invalid,
> -                     bool account_failed);
> +                      bool account_failed, unsigned 
> latency_log_threshold_ms);
>  void block_acct_cleanup(BlockAcctStats *stats);
>  void block_acct_add_interval(BlockAcctStats *stats, unsigned 
> interval_length);
>  BlockAcctTimedStats *block_acct_interval_next(BlockAcctStats *stats,
> diff --git a/slirp b/slirp
> index ce94eba204..2faae0f778 160000
> --- a/slirp
> +++ b/slirp
> @@ -1 +1 @@
> -Subproject commit ce94eba2042d52a0ba3d9e252ebce86715e94275
> +Subproject commit 2faae0f778f818fadc873308f983289df697eb93

SLiRP change unrelated I presume...