On Tuesday 09 November 2010 19:08:14 Stefano Stabellini wrote:
> On Wed, 3 Nov 2010, Christoph Egger wrote:
> > No, this patch has no effect for me.
> > In libxl__fill_dom0_memory_info(), the code path goes that way:
> >
> > t = xs_transaction_start(ctx->xsh);
> >
> > target = libxl__xs_read(gc, t, target_path);
> > if (target) { <-- target contains "5"
> > *target_memkb = strtoul(target, &endptr, 10);
> > if (*endptr != '\0') { <-- *endptr contains '\0'
> > LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR,
> > "invalid memory target %s from %s\n", target,
> > target_path);
> > rc = ERROR_FAIL;
> > goto out;
> > }
> > rc = 0;
> > goto out; <-- take this jump with rc being 0
> > }
>
> The problem you are having is that somebody in your system is setting a
> target for dom0 without setting freemem-slack. Are you still running
> xend at boot?
Yes, I do.
Xen is booted with dom0_mem.
Dom0 has autoballooning disabled in the kernel.
> Currently libxl__fill_dom0_memory_info assumes that both values are set
> initially at the same time (by libxl__fill_dom0_memory_info).
> This patch should fix the issue, I would appreciate if you could test
> it.
>
> ---
>
>
> libxl: do not assume target and freemem-slack are written at the same time
>
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
>
> diff -r 7188d1e4b0e1 tools/libxl/libxl.c
> --- a/tools/libxl/libxl.c Tue Nov 09 12:00:05 2010 +0000
> +++ b/tools/libxl/libxl.c Tue Nov 09 18:05:52 2010 +0000
> @@ -2779,18 +2779,25 @@ static int libxl__fill_dom0_memory_info(
> int rc;
> libxl_dominfo info;
> libxl_physinfo physinfo;
> - char *target = NULL, *endptr = NULL;
> + char *target = NULL, *staticmax = NULL, *freememslack = NULL, *endptr
> = NULL; char *target_path = "/local/domain/0/memory/target";
> char *max_path = "/local/domain/0/memory/static-max";
> char *free_mem_slack_path = "/local/domain/0/memory/freemem-slack";
> xs_transaction_t t;
> libxl_ctx *ctx = libxl__gc_owner(gc);
> - uint32_t free_mem_slack = 0;
> + uint32_t free_mem_slack_kb = 0;
>
> retry_transaction:
> t = xs_transaction_start(ctx->xsh);
>
> target = libxl__xs_read(gc, t, target_path);
> + staticmax = libxl__xs_read(gc, t, target_path);
> + freememslack = libxl__xs_read(gc, t, target_path);
> + if (target && staticmax && freememslack) {
> + rc = 0;
> + goto out;
> + }
*target, *staticmax and *freememslack contain the value "5".
So with this patch, rc always returns 0 from there.
Christoph
> +
> if (target) {
> *target_memkb = strtoul(target, &endptr, 10);
> if (*endptr != '\0') {
> @@ -2799,38 +2806,43 @@ retry_transaction:
> rc = ERROR_FAIL;
> goto out;
> }
> - rc = 0;
> - goto out;
> }
>
> rc = libxl_domain_info(ctx, &info, 0);
> if (rc < 0)
> - return rc;
> + goto out;
>
> rc = libxl_get_physinfo(ctx, &physinfo);
> if (rc < 0)
> - return rc;
> -
> - libxl__xs_write(gc, t, target_path, "%"PRIu32,
> - (uint32_t) info.current_memkb);
> - libxl__xs_write(gc, t, max_path, "%"PRIu32,
> - (uint32_t) info.max_memkb);
> -
> - free_mem_slack = (uint32_t) (PAGE_TO_MEMKB(physinfo.total_pages) -
> - info.current_memkb);
> - /* From empirical measurements the free_mem_slack shouldn't be more
> - * than 15% of the total memory present on the system. */
> - if (free_mem_slack > PAGE_TO_MEMKB(physinfo.total_pages) * 0.15)
> - free_mem_slack = PAGE_TO_MEMKB(physinfo.total_pages) * 0.15;
> - libxl__xs_write(gc, t, free_mem_slack_path, "%"PRIu32,
> free_mem_slack); -
> - *target_memkb = (uint32_t) info.current_memkb;
> + goto out;
> +
> + if (target == NULL) {
> + libxl__xs_write(gc, t, target_path, "%"PRIu32,
> + (uint32_t) info.current_memkb);
> + *target_memkb = (uint32_t) info.current_memkb;
> + }
> + if (staticmax == NULL)
> + libxl__xs_write(gc, t, max_path, "%"PRIu32,
> + (uint32_t) info.max_memkb);
> +
> + if (freememslack == NULL) {
> + free_mem_slack_kb = (uint32_t)
> (PAGE_TO_MEMKB(physinfo.total_pages) - +
> info.current_memkb);
> + /* From empirical measurements the free_mem_slack shouldn't be
> more + * than 15% of the total memory present on the system. */ +
> if (free_mem_slack_kb > PAGE_TO_MEMKB(physinfo.total_pages) * 0.15) +
> free_mem_slack_kb = PAGE_TO_MEMKB(physinfo.total_pages) * 0.15; +
> libxl__xs_write(gc, t, free_mem_slack_path, "%"PRIu32,
> free_mem_slack_kb); + }
> rc = 0;
>
> out:
> - if (!xs_transaction_end(ctx->xsh, t, 0))
> + if (!xs_transaction_end(ctx->xsh, t, 0)) {
> if (errno == EAGAIN)
> goto retry_transaction;
> + else
> + rc = ERROR_FAIL;
> + }
>
>
> return rc;
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