LU-14424 Revert "LU-9679 osc: simplify osc_extent_find()"

It looks like there are performance regressions atttributed to this patch.

This reverts commit 80e21cce3dd6748fd760786cafe9c26d502fd74f.

Change-Id: I55e0abd50573dd82a9d216f9c3b01483f99c3223
Signed-off-by: Oleg Drokin <green@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/41498
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: John L. Hammond <jhammond@whamcloud.com>

diff --git a/lustre/osc/osc_cache.c b/lustre/osc/osc_cache.c
index 7de0073..9c29955 100644 (file)
--- a/lustre/osc/osc_cache.c
+++ b/lustre/osc/osc_cache.c
@@ -537,14 +537,6 @@ static int osc_extent_merge(const struct lu_env *env, struct osc_extent *cur,
        if (cur->oe_max_end != victim->oe_max_end)
                return -ERANGE;
 
        if (cur->oe_max_end != victim->oe_max_end)
                return -ERANGE;
 

-       /*
-        * In the rare case max_pages_per_rpc (mppr) is changed, don't
-        * merge extents until after old ones have been sent, or the
-        * "extents are aligned to RPCs" checks are unhappy.
-        */
-       if (cur->oe_mppr != victim->oe_mppr)
-               return -ERANGE;
-

        LASSERT(cur->oe_dlmlock == victim->oe_dlmlock);
        ppc_bits = osc_cli(obj)->cl_chunkbits - PAGE_SHIFT;
        chunk_start = cur->oe_start >> ppc_bits;
        LASSERT(cur->oe_dlmlock == victim->oe_dlmlock);
        ppc_bits = osc_cli(obj)->cl_chunkbits - PAGE_SHIFT;
        chunk_start = cur->oe_start >> ppc_bits;


@@ -570,6 +562,7 @@ static int osc_extent_merge(const struct lu_env *env, struct osc_extent *cur,
        cur->oe_urgent   |= victim->oe_urgent;
        cur->oe_memalloc |= victim->oe_memalloc;
        list_splice_init(&victim->oe_pages, &cur->oe_pages);
        cur->oe_urgent   |= victim->oe_urgent;
        cur->oe_memalloc |= victim->oe_memalloc;
        list_splice_init(&victim->oe_pages, &cur->oe_pages);

+       list_del_init(&victim->oe_link);

        victim->oe_nr_pages = 0;
 
        osc_extent_get(victim);
        victim->oe_nr_pages = 0;
 
        osc_extent_get(victim);


@@ -697,7 +690,7 @@ static struct osc_extent *osc_extent_find(const struct lu_env *env,
                cur->oe_start = descr->cld_start;
        if (cur->oe_end > max_end)
                cur->oe_end = max_end;
                cur->oe_start = descr->cld_start;
        if (cur->oe_end > max_end)
                cur->oe_end = max_end;

-       cur->oe_grants  = chunksize + cli->cl_grant_extent_tax;
+       cur->oe_grants  = 0;

        cur->oe_mppr    = max_pages;
        if (olck->ols_dlmlock != NULL) {
                LASSERT(olck->ols_hold);
        cur->oe_mppr    = max_pages;
        if (olck->ols_dlmlock != NULL) {
                LASSERT(olck->ols_hold);


@@ -765,21 +758,54 @@ restart:
                         * flushed, try next one. */
                        continue;
 
                         * flushed, try next one. */
                        continue;
 

-               if (osc_extent_merge(env, ext, cur) == 0) {
+               /* check if they belong to the same rpc slot before trying to
+                * merge. the extents are not overlapped and contiguous at
+                * chunk level to get here. */
+               if (ext->oe_max_end != max_end)
+                       /* if they don't belong to the same RPC slot or
+                        * max_pages_per_rpc has ever changed, do not merge. */
+                       continue;
+
+               /* check whether maximum extent size will be hit */
+               if ((ext_chk_end - ext_chk_start + 1 + 1) << ppc_bits >
+                   cli->cl_max_extent_pages)
+                       continue;
+
+               /* it's required that an extent must be contiguous at chunk
+                * level so that we know the whole extent is covered by grant
+                * (the pages in the extent are NOT required to be contiguous).
+                * Otherwise, it will be too much difficult to know which
+                * chunks have grants allocated. */
+
+               /* try to do front merge - extend ext's start */
+               if (chunk + 1 == ext_chk_start) {
+                       /* ext must be chunk size aligned */
+                       EASSERT((ext->oe_start & ~chunk_mask) == 0, ext);
+
+                       /* pull ext's start back to cover cur */
+                       ext->oe_start   = cur->oe_start;
+                       ext->oe_grants += chunksize;

                        LASSERT(*grants >= chunksize);
                        *grants -= chunksize;
                        LASSERT(*grants >= chunksize);
                        *grants -= chunksize;

+

                        found = osc_extent_hold(ext);
                        found = osc_extent_hold(ext);

+               } else if (chunk == ext_chk_end + 1) {
+                       /* rear merge */
+                       ext->oe_end     = cur->oe_end;
+                       ext->oe_grants += chunksize;
+                       LASSERT(*grants >= chunksize);
+                       *grants -= chunksize;

 
 

-                       /*
-                        * Try to merge with the next one too because we
-                        * might have just filled in a gap.
-                        */
+                       /* try to merge with the next one because we just fill
+                        * in a gap */

                        if (osc_extent_merge(env, ext, next_extent(ext)) == 0)
                                /* we can save extent tax from next extent */
                                *grants += cli->cl_grant_extent_tax;
 
                        if (osc_extent_merge(env, ext, next_extent(ext)) == 0)
                                /* we can save extent tax from next extent */
                                *grants += cli->cl_grant_extent_tax;
 

-                       break;
+                       found = osc_extent_hold(ext);

                }
                }

+               if (found != NULL)
+                       break;

        }
 
        osc_extent_tree_dump(D_CACHE, obj);
        }
 
        osc_extent_tree_dump(D_CACHE, obj);


@@ -793,6 +819,7 @@ restart:
        } else if (conflict == NULL) {
                /* create a new extent */
                EASSERT(osc_extent_is_overlapped(obj, cur) == 0, cur);
        } else if (conflict == NULL) {
                /* create a new extent */
                EASSERT(osc_extent_is_overlapped(obj, cur) == 0, cur);

+               cur->oe_grants = chunksize + cli->cl_grant_extent_tax;

                LASSERT(*grants >= cur->oe_grants);
                *grants -= cur->oe_grants;
 
                LASSERT(*grants >= cur->oe_grants);
                *grants -= cur->oe_grants;