On Thu, Oct 6, 2022 at 3:09 PM Jonathan Derrick
<jonathan.derrick@xxxxxxxxx> wrote:
[...]
> diff --git a/drivers/md/md-bitmap.h b/drivers/md/md-bitmap.h
> index cfd7395de8fd..e0aeedbdde17 100644
> --- a/drivers/md/md-bitmap.h
> +++ b/drivers/md/md-bitmap.h
> @@ -11,10 +11,12 @@
> /* version 4 insists the bitmap is in little-endian order
> * with version 3, it is host-endian which is non-portable
> * Version 5 is currently set only for clustered devices
> ++ * Version 6 supports the flush-chunks threshold
> */
> #define BITMAP_MAJOR_HI 4
> #define BITMAP_MAJOR_CLUSTERED 5
> #define BITMAP_MAJOR_HOSTENDIAN 3
> +#define BITMAP_MAJOR_CHUNKFLUSH 6
>
> /*
> * in-memory bitmap:
> @@ -135,7 +137,8 @@ typedef struct bitmap_super_s {
> * reserved for the bitmap. */
> __le32 nodes; /* 68 the maximum number of nodes in cluster. */
> __u8 cluster_name[64]; /* 72 cluster name to which this md belongs */
> - __u8 pad[256 - 136]; /* set to zero */
> + __le32 daemon_flush_chunks; /* 136 dirty chunks between flushes */
> + __u8 pad[256 - 140]; /* set to zero */
> } bitmap_super_t;
Do we really need this to be persistent? How about we configure it at run
time via a sysfs file?
Also, please share more data on the performance benefit of the set.
Thanks,
Song
>
> /* notes:
> diff --git a/drivers/md/md.h b/drivers/md/md.h
> index b4e2d8b87b61..d25574e46283 100644
> --- a/drivers/md/md.h
> +++ b/drivers/md/md.h
> @@ -497,6 +497,7 @@ struct mddev {
> struct mutex mutex;
> unsigned long chunksize;
> unsigned long daemon_sleep; /* how many jiffies between updates? */
> + unsigned int daemon_flush_chunks; /* how many dirty chunks between updates */
> unsigned long max_write_behind; /* write-behind mode */
> int external;
> int nodes; /* Maximum number of nodes in the cluster */
> --
> 2.31.1
>
