xen/libxc-sr-save-rec_pfns.patch

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From: Olaf Hering <olaf@aepfle.de>
Date: Fri, 23 Oct 2020 11:34:00 +0200
Subject: libxc sr save rec_pfns
tools: save: preallocate rec_pfns array
Remove repeated allocation from migration loop. There will never be
more than MAX_BATCH_SIZE pages to process in a batch.
Allocate the space once.
Signed-off-by: Olaf Hering <olaf@aepfle.de>
---
tools/libs/guest/xg_sr_common.h | 1 +
tools/libs/guest/xg_sr_save.c | 28 +++++++++++-----------------
2 files changed, 12 insertions(+), 17 deletions(-)
--- a/tools/libs/guest/xg_sr_common.h
+++ b/tools/libs/guest/xg_sr_common.h
@@ -248,6 +248,7 @@ struct xc_sr_context
xen_pfn_t *types;
int *errors;
struct iovec *iov;
+ uint64_t *rec_pfns;
unsigned int nr_batch_pfns;
unsigned long *deferred_pages;
unsigned long nr_deferred_pages;
--- a/tools/libs/guest/xg_sr_save.c
+++ b/tools/libs/guest/xg_sr_save.c
@@ -95,7 +95,6 @@ static int write_batch(struct xc_sr_cont
unsigned int i, p, nr_pages = 0, nr_pages_mapped = 0;
unsigned int nr_pfns = ctx->save.nr_batch_pfns;
void *page, *orig_page;
- uint64_t *rec_pfns = NULL;
int iovcnt = 0;
struct xc_sr_rec_page_data_header hdr = { 0 };
struct xc_sr_record rec = {
@@ -202,22 +201,15 @@ static int write_batch(struct xc_sr_cont
}
}
- rec_pfns = malloc(nr_pfns * sizeof(*rec_pfns));
- if ( !rec_pfns )
- {
- ERROR("Unable to allocate %zu bytes of memory for page data pfn list",
- nr_pfns * sizeof(*rec_pfns));
- goto err;
- }
-
hdr.count = nr_pfns;
rec.length = sizeof(hdr);
- rec.length += nr_pfns * sizeof(*rec_pfns);
+ rec.length += nr_pfns * sizeof(*ctx->save.rec_pfns);
rec.length += nr_pages * PAGE_SIZE;
for ( i = 0; i < nr_pfns; ++i )
- rec_pfns[i] = ((uint64_t)(ctx->save.types[i]) << 32) | ctx->save.batch_pfns[i];
+ ctx->save.rec_pfns[i] = ((uint64_t)(ctx->save.types[i]) << 32) |
+ ctx->save.batch_pfns[i];
ctx->save.iov[0].iov_base = &rec.type;
ctx->save.iov[0].iov_len = sizeof(rec.type);
@@ -228,12 +220,13 @@ static int write_batch(struct xc_sr_cont
ctx->save.iov[2].iov_base = &hdr;
ctx->save.iov[2].iov_len = sizeof(hdr);
- ctx->save.iov[3].iov_base = rec_pfns;
- ctx->save.iov[3].iov_len = nr_pfns * sizeof(*rec_pfns);
+ ctx->save.iov[3].iov_base = ctx->save.rec_pfns;
+ ctx->save.iov[3].iov_len = nr_pfns * sizeof(*ctx->save.rec_pfns);
iovcnt = 4;
ctx->save.pages_sent += nr_pages;
- ctx->save.overhead_sent += sizeof(rec) + sizeof(hdr) + nr_pfns * sizeof(*rec_pfns);
+ ctx->save.overhead_sent += sizeof(rec) + sizeof(hdr) +
+ nr_pfns * sizeof(*ctx->save.rec_pfns);
if ( nr_pages )
{
@@ -260,7 +253,6 @@ static int write_batch(struct xc_sr_cont
rc = ctx->save.nr_batch_pfns = 0;
err:
- free(rec_pfns);
if ( guest_mapping )
xenforeignmemory_unmap(xch->fmem, guest_mapping, nr_pages_mapped);
for ( i = 0; local_pages && i < nr_pfns; ++i )
@@ -843,11 +835,12 @@ static int setup(struct xc_sr_context *c
ctx->save.types = malloc(MAX_BATCH_SIZE * sizeof(*ctx->save.types));
ctx->save.errors = malloc(MAX_BATCH_SIZE * sizeof(*ctx->save.errors));
ctx->save.iov = malloc((4 + MAX_BATCH_SIZE) * sizeof(*ctx->save.iov));
+ ctx->save.rec_pfns = malloc(MAX_BATCH_SIZE * sizeof(*ctx->save.rec_pfns));
ctx->save.deferred_pages = bitmap_alloc(ctx->save.p2m_size);
if ( !ctx->save.batch_pfns || !ctx->save.mfns || !ctx->save.types ||
- !ctx->save.errors || !ctx->save.iov || !dirty_bitmap ||
- !ctx->save.deferred_pages )
+ !ctx->save.errors || !ctx->save.iov || !ctx->save.rec_pfns ||
+ !dirty_bitmap || !ctx->save.deferred_pages )
{
ERROR("Unable to allocate memory for dirty bitmaps, batch pfns and"
" deferred pages");
@@ -878,6 +871,7 @@ static void cleanup(struct xc_sr_context
xc_hypercall_buffer_free_pages(xch, dirty_bitmap,
NRPAGES(bitmap_size(ctx->save.p2m_size)));
free(ctx->save.deferred_pages);
+ free(ctx->save.rec_pfns);
free(ctx->save.iov);
free(ctx->save.errors);
free(ctx->save.types);