Messages in this thread | | | From | David Howells <> | Subject | Re: [PATCH 00/10] MM changes to improve swap-over-NFS support | Date | Thu, 31 Mar 2022 09:13:25 +0100 |
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NeilBrown <neilb@suse.de> wrote:
> Assorted improvements for swap-via-filesystem. > > This is a resend of these patches, rebased on current HEAD. > The only substantial changes is that swap_dirty_folio has replaced > swap_set_page_dirty. > > Currently swap-via-fs (SWP_FS_OPS) doesn't work for any filesystem. It > has previously worked for NFS but that broke a few releases back. > This series changes to use a new ->swap_rw rather than ->readpage and > ->direct_IO. It also makes other improvements. > > There is a companion series already in linux-next which fixes various > issues with NFS. Once both series land, a final patch is needed which > changes NFS over to use ->swap_rw.
This seems to work by running sufficient copies of the attached program in parallel to overwhelm the amount of ordinary RAM.
Tested-by: David Howells <dhowells@redhat.com> --- #include <stdbool.h> #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <sys/mman.h>
int main() { unsigned int pid = getpid(), iterations = 0; size_t i, j, size = 1024 * 1024 * 1024; char *p; bool mismatch;
p = malloc(size); if (!p) { perror("malloc"); exit(1); }
srand(pid); for (i = 0; i < size; i += 4) *(unsigned int *)(p + i) = rand(); do { for (j = 0; j < 16; j++) { for (i = 0; i < size; i += 4096) *(unsigned int *)(p + i) += 1; iterations++; }
mismatch = false; srand(pid); for (i = 0; i < size; i += 4) { unsigned int r = rand(); unsigned int v = *(unsigned int *)(p + i);
if (i % 4096 == 0) v -= iterations;
if (v != r) { fprintf(stderr, "mismatch %zx: %x != %x (diff %x)\n", i, v, r, v - r); mismatch = true; } } } while (!mismatch);
exit(1); }
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