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authorDave Chinner <dchinner@redhat.com>2010-08-24 11:45:53 +1000
committerDave Chinner <david@fromorbit.com>2010-08-24 11:45:53 +1000
commit3b93c7aaefc05ee2a75e2726929b01a321402984 (patch)
tree736a4017e86d65598ae7b30cb11412afd66f9629 /fs
parenta44f13edf0ebb4e41942d0f16ca80489dcf6659d (diff)
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xfs: don't do memory allocation under the CIL context lock
Formatting items requires memory allocation when using delayed logging. Currently that memory allocation is done while holding the CIL context lock in read mode. This means that if memory allocation takes some time (e.g. enters reclaim), we cannot push on the CIL until the allocation(s) required by formatting complete. This can stall CIL pushes for some time, and once a push is stalled so are all new transaction commits. Fix this splitting the item formatting into two steps. The first step which does the allocation and memcpy() into the allocated buffer is now done outside the CIL context lock, and only the CIL insert is done inside the CIL context lock. This avoids the stall issue. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
Diffstat (limited to 'fs')
-rw-r--r--fs/xfs/xfs_log_cil.c34
1 files changed, 26 insertions, 8 deletions
diff --git a/fs/xfs/xfs_log_cil.c b/fs/xfs/xfs_log_cil.c
index 9768f2437bb..ed575fb4b49 100644
--- a/fs/xfs/xfs_log_cil.c
+++ b/fs/xfs/xfs_log_cil.c
@@ -270,15 +270,10 @@ xlog_cil_insert(
static void
xlog_cil_format_items(
struct log *log,
- struct xfs_log_vec *log_vector,
- struct xlog_ticket *ticket,
- xfs_lsn_t *start_lsn)
+ struct xfs_log_vec *log_vector)
{
struct xfs_log_vec *lv;
- if (start_lsn)
- *start_lsn = log->l_cilp->xc_ctx->sequence;
-
ASSERT(log_vector);
for (lv = log_vector; lv; lv = lv->lv_next) {
void *ptr;
@@ -302,9 +297,24 @@ xlog_cil_format_items(
ptr += vec->i_len;
}
ASSERT(ptr == lv->lv_buf + lv->lv_buf_len);
+ }
+}
+static void
+xlog_cil_insert_items(
+ struct log *log,
+ struct xfs_log_vec *log_vector,
+ struct xlog_ticket *ticket,
+ xfs_lsn_t *start_lsn)
+{
+ struct xfs_log_vec *lv;
+
+ if (start_lsn)
+ *start_lsn = log->l_cilp->xc_ctx->sequence;
+
+ ASSERT(log_vector);
+ for (lv = log_vector; lv; lv = lv->lv_next)
xlog_cil_insert(log, ticket, lv->lv_item, lv);
- }
}
static void
@@ -612,9 +622,17 @@ xfs_log_commit_cil(
return XFS_ERROR(EIO);
}
+ /*
+ * do all the hard work of formatting items (including memory
+ * allocation) outside the CIL context lock. This prevents stalling CIL
+ * pushes when we are low on memory and a transaction commit spends a
+ * lot of time in memory reclaim.
+ */
+ xlog_cil_format_items(log, log_vector);
+
/* lock out background commit */
down_read(&log->l_cilp->xc_ctx_lock);
- xlog_cil_format_items(log, log_vector, tp->t_ticket, commit_lsn);
+ xlog_cil_insert_items(log, log_vector, tp->t_ticket, commit_lsn);
/* check we didn't blow the reservation */
if (tp->t_ticket->t_curr_res < 0)