On Friday 27 August 2010 13:19:19 Stefano Stabellini wrote:
> xl: free memory before building a domain
>
> Free the needed amount of memory before proceeding with the domain
> build.
> Use a filelock to prevent other xl instances from conflicting during
> this operation.
>
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
>
> diff -r b80a1688b5c9 tools/examples/xl.conf
> --- a/tools/examples/xl.conf Thu Aug 26 18:03:20 2010 +0100
> +++ b/tools/examples/xl.conf Thu Aug 26 18:26:04 2010 +0100
> @@ -3,3 +3,6 @@
> # automatically balloon down dom0 when xen doesn't have enough free
> # memory to create a domain
> autoballon=1
> +
> +# full path of the lockfile used by xl during domain creation
> +lockfile="/var/lock/xl"
> diff -r b80a1688b5c9 tools/libxl/xl.c
> --- a/tools/libxl/xl.c Thu Aug 26 18:03:20 2010 +0100
> +++ b/tools/libxl/xl.c Thu Aug 26 18:26:04 2010 +0100
> @@ -34,6 +34,7 @@
>
> xentoollog_logger_stdiostream *logger;
> int autoballoon = 1;
> +char *lockfile = "/var/lock/xl";
NetBSD doesn't have /var/lock. Is it ok to use /var/lib ?
Christoph
>
> static xentoollog_level minmsglevel = XTL_PROGRESS;
>
> @@ -44,6 +45,7 @@ static void parse_global_config(const ch
> long l;
> XLU_Config *config;
> int e;
> + const char *buf;
>
> config = xlu_cfg_init(stderr, configfile);
> if (!config) {
> @@ -60,6 +62,9 @@ static void parse_global_config(const ch
> if (!xlu_cfg_get_long (config, "autoballoon", &l))
> autoballoon = l;
>
> + if (!xlu_cfg_get_string (config, "lockfile", &buf))
> + lockfile = strdup(buf);
> +
> xlu_cfg_destroy(config);
> }
>
> diff -r b80a1688b5c9 tools/libxl/xl.h
> --- a/tools/libxl/xl.h Thu Aug 26 18:03:20 2010 +0100
> +++ b/tools/libxl/xl.h Thu Aug 26 18:26:04 2010 +0100
> @@ -92,5 +92,6 @@ extern xentoollog_logger_stdiostream *lo
>
> /* global options */
> extern int autoballoon;
> +extern char *lockfile;
>
> #endif /* XL_H */
> diff -r b80a1688b5c9 tools/libxl/xl_cmdimpl.c
> --- a/tools/libxl/xl_cmdimpl.c Thu Aug 26 18:03:20 2010 +0100
> +++ b/tools/libxl/xl_cmdimpl.c Thu Aug 26 18:26:04 2010 +0100
> @@ -68,6 +68,7 @@ libxl_ctx ctx;
> /* when we operate on a domain, it is this one: */
> static uint32_t domid;
> static const char *common_domname;
> +static int fd_lock = -1;
>
>
> static const char savefileheader_magic[32]=
> @@ -234,6 +235,65 @@ static void find_domain(const char *p)
> common_domname = was_name ? p : libxl_domid_to_name(&ctx, domid);
> }
>
> +static int acquire_lock(void)
> +{
> + int rc;
> + struct flock fl;
> +
> + /* lock already acquired */
> + if (fd_lock >= 0)
> + return ERROR_INVAL;
> +
> + fl.l_type = F_WRLCK;
> + fl.l_whence = SEEK_SET;
> + fl.l_start = 0;
> + fl.l_len = 0;
> + fd_lock = open(lockfile, O_WRONLY|O_CREAT, S_IWUSR);
> + if (fd_lock < 0) {
> + fprintf(stderr, "cannot open the lockfile %s errno=%d\n",
> lockfile, errno); + return ERROR_FAIL;
> + }
> +get_lock:
> + rc = fcntl(fd_lock, F_SETLKW, &fl);
> + if (rc < 0 && errno == EINTR)
> + goto get_lock;
> + if (rc < 0) {
> + fprintf(stderr, "cannot acquire lock %s errno=%d\n", lockfile,
> errno); + rc = ERROR_FAIL;
> + } else
> + rc = 0;
> + return rc;
> +}
> +
> +static int release_lock(void)
> +{
> + int rc;
> + struct flock fl;
> +
> + /* lock not acquired */
> + if (fd_lock < 0)
> + return ERROR_INVAL;
> +
> +release_lock:
> + fl.l_type = F_UNLCK;
> + fl.l_whence = SEEK_SET;
> + fl.l_start = 0;
> + fl.l_len = 0;
> +
> + rc = fcntl(fd_lock, F_SETLKW, &fl);
> + if (rc < 0 && errno == EINTR)
> + goto release_lock;
> + if (rc < 0) {
> + fprintf(stderr, "cannot release lock %s, errno=%d\n", lockfile,
> errno); + rc = ERROR_FAIL;
> + } else
> + rc = 0;
> + close(fd_lock);
> + fd_lock = -1;
> +
> + return rc;
> +}
> +
> #define LOG(_f, _a...) dolog(__FILE__, __LINE__, __func__, _f "\n",
> ##_a)
>
> static void dolog(const char *file, int line, const char *func, char *fmt,
> ...) @@ -1209,6 +1269,48 @@ struct domain_create {
> char **migration_domname_r;
> };
>
> +static int freemem(libxl_domain_build_info *b_info,
> libxl_device_model_info *dm_info) +{
> + int rc, retries = 3;
> + uint32_t need_memkb, free_memkb;
> +
> + if (!autoballoon)
> + return 0;
> +
> + rc = libxl_domain_need_memory(&ctx, b_info, dm_info, &need_memkb);
> + if (rc < 0)
> + return rc;
> +
> + do {
> + rc = libxl_get_free_memory(&ctx, &free_memkb);
> + if (rc < 0)
> + return rc;
> +
> + if (free_memkb >= need_memkb)
> + return 0;
> +
> + rc = libxl_set_relative_memory_target(&ctx, 0, free_memkb -
> need_memkb, 0); + if (rc < 0)
> + return rc;
> +
> + rc = libxl_wait_for_free_memory(&ctx, domid, need_memkb, 10);
> + if (!rc)
> + return 0;
> + else if (rc != ERROR_NOMEM)
> + return rc;
> +
> + /* the memory target has been reached but the free memory is still
> + * not enough: loop over again */
> + rc = libxl_wait_for_memory_target(&ctx, 0, 1);
> + if (rc < 0)
> + return rc;
> +
> + retries--;
> + } while (retries > 0);
> +
> + return ERROR_NOMEM;
> +}
> +
> static int create_domain(struct domain_create *dom_info)
> {
> struct domain_config d_config;
> @@ -1367,6 +1469,17 @@ static int create_domain(struct domain_c
> start:
> domid = 0;
>
> + rc = acquire_lock();
> + if (rc < 0)
> + goto error_out;
> +
> + ret = freemem(&d_config.b_info, &dm_info);
> + if (ret < 0) {
> + fprintf(stderr, "failed to free memory for the domain\n");
> + ret = ERROR_FAIL;
> + goto error_out;
> + }
> +
> ret = libxl_domain_make(&ctx, &d_config.c_info, &domid);
> if (ret) {
> fprintf(stderr, "cannot make domain: %d\n", ret);
> @@ -1475,6 +1588,8 @@ start:
> goto error_out;
> }
>
> + release_lock();
> +
> if (!paused)
> libxl_domain_unpause(&ctx, domid);
>
> @@ -1612,6 +1727,7 @@ start:
> }
>
> error_out:
> + release_lock();
> if (domid)
> libxl_domain_destroy(&ctx, domid, 0);
>
>
> _______________________________________________
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> Xen-devel@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-devel
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