Grow: use large block count and make sure stripe cache can hold it.

The bigger the backup is, the fast it goes to some extend.

16Meg is fairly arbitrary

Signed-off-by: NeilBrown <neilb@suse.de>

diff --git a/Grow.c b/Grow.c
index 9204edf6145a7fa83ebbbe4aba235f8a2d1e622d..8e6e7f775403c38721b5dbbcd3aedb3c3d8078d2 100644 (file)
--- a/Grow.c
+++ b/Grow.c
@@ -908,9 +908,11 @@ int Grow_reshape(char *devname, int fd, int quiet, char *backup_file,
                if (ndata == odata) {
                        /* Make 'blocks' bigger for better throughput, but
                         * not so big that we reject it below.
+                        * Try for 16 megabytes
                         */
-                       if (blocks * 32 < sra->component_size)
-                               blocks *= 16;
+                       while (blocks * 32 < sra->component_size &&
+                              blocks < 16*1024*2)
+                              blocks *= 2;
                } else
                        fprintf(stderr, Name ": Need to backup %luK of critical "
                                "section..\n", blocks/2);
@@ -1026,6 +1028,9 @@ int Grow_reshape(char *devname, int fd, int quiet, char *backup_file,
                
                cache = (nchunk < ochunk) ? ochunk : nchunk;
                cache = cache * 4 / 4096;
+               if (cache < blocks / 8 / odisks + 16)
+                       /* Make it big enough to hold 'blocks' */
+                       cache = blocks / 8 / odisks + 16;
                if (sra->cache_size < cache)
                        sysfs_set_num(sra, NULL, "stripe_cache_size",
                                      cache+1);
@@ -1873,6 +1878,7 @@ int Grow_continue(int mdfd, struct supertype *st, struct mdinfo *info,
        int d;
        struct mdinfo *sra, *sd;
        int rv;
+       int cache;
        int done = 0;
 
        err = sysfs_set_str(info, NULL, "array_state", "readonly");
@@ -1908,10 +1914,28 @@ int Grow_continue(int mdfd, struct supertype *st, struct mdinfo *info,
        /* LCM == product / GCD */
        blocks = ochunk/512 * nchunk/512 * odata * ndata / a;
 
+       sra = sysfs_read(-1, devname2devnum(info->sys_name),
+                        GET_COMPONENT|GET_DEVS|GET_OFFSET|GET_STATE|
+                        GET_CACHE);
+
+
        if (ndata == odata)
-               blocks *= 16;
+               while (blocks * 32 < sra->component_size &&
+                      blocks < 16*1024*2)
+                       blocks *= 2;
        stripes = blocks / (info->array.chunk_size/512) / odata;
 
+       /* check that the internal stripe cache is
+        * large enough, or it won't work.
+        */
+       cache = (nchunk < ochunk) ? ochunk : nchunk;
+       cache = cache * 4 / 4096;
+       if (cache < blocks / 8 / odisks + 16)
+               /* Make it big enough to hold 'blocks' */
+               cache = blocks / 8 / odisks + 16;
+       if (sra->cache_size < cache)
+               sysfs_set_num(sra, NULL, "stripe_cache_size",
+                             cache+1);
 
        memset(&bsb, 0, 512);
        memcpy(bsb.magic, "md_backup_data-1", 16);
@@ -1927,10 +1951,6 @@ int Grow_continue(int mdfd, struct supertype *st, struct mdinfo *info,
        for (d=0; d<odisks; d++)
                fds[d] = -1;
 
-       sra = sysfs_read(-1, devname2devnum(info->sys_name),
-                        GET_COMPONENT|GET_DEVS|GET_OFFSET|GET_STATE|
-                        GET_CACHE);
-
        for (sd = sra->devs; sd; sd = sd->next) {
                if (sd->disk.state & (1<<MD_DISK_FAULTY))
                        continue;