Commit ef36fa14 authored by Marcelo Tosatti's avatar Marcelo Tosatti Committed by Paolo Bonzini
Browse files

qemu: mempath: prefault pages manually (v4) 



v4: s/fail/failed/  (Peter Maydell)

Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
parent fb541ca5

exec.c

+47 −12
Original line number Diff line number Diff line
@@ -904,6 +904,13 @@ static long gethugepagesize(const char *path) 
    return fs.f_bsize;

}



static sigjmp_buf sigjump;



static void sigbus_handler(int signal)

{

    siglongjmp(sigjump, 1);

}



static void *file_ram_alloc(RAMBlock *block,

                            ram_addr_t memory,

                            const char *path)
@@ -913,9 +920,6 @@ static void *file_ram_alloc(RAMBlock *block, 
    char *c;

    void *area;

    int fd;

#ifdef MAP_POPULATE

    int flags;

#endif

    unsigned long hpagesize;



    hpagesize = gethugepagesize(path);
@@ -963,21 +967,52 @@ static void *file_ram_alloc(RAMBlock *block, 
    if (ftruncate(fd, memory))

        perror("ftruncate");



#ifdef MAP_POPULATE

    /* NB: MAP_POPULATE won't exhaustively alloc all phys pages in the case

     * MAP_PRIVATE is requested.  For mem_prealloc we mmap as MAP_SHARED

     * to sidestep this quirk.

     */

    flags = mem_prealloc ? MAP_POPULATE | MAP_SHARED : MAP_PRIVATE;

    area = mmap(0, memory, PROT_READ | PROT_WRITE, flags, fd, 0);

#else

    area = mmap(0, memory, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);

#endif

    if (area == MAP_FAILED) {

        perror("file_ram_alloc: can't mmap RAM pages");

        close(fd);

        return (NULL);

    }



    if (mem_prealloc) {

        int ret, i;

        struct sigaction act, oldact;

        sigset_t set, oldset;



        memset(&act, 0, sizeof(act));

        act.sa_handler = &sigbus_handler;

        act.sa_flags = 0;



        ret = sigaction(SIGBUS, &act, &oldact);

        if (ret) {

            perror("file_ram_alloc: failed to install signal handler");

            exit(1);

        }



        /* unblock SIGBUS */

        sigemptyset(&set);

        sigaddset(&set, SIGBUS);

        pthread_sigmask(SIG_UNBLOCK, &set, &oldset);



        if (sigsetjmp(sigjump, 1)) {

            fprintf(stderr, "file_ram_alloc: failed to preallocate pages\n");

            exit(1);

        }



        /* MAP_POPULATE silently ignores failures */

        for (i = 0; i < (memory/hpagesize)-1; i++) {

            memset(area + (hpagesize*i), 0, 1);

        }



        ret = sigaction(SIGBUS, &oldact, NULL);

        if (ret) {

            perror("file_ram_alloc: failed to reinstall signal handler");

            exit(1);

        }



        pthread_sigmask(SIG_SETMASK, &oldset, NULL);

    }



    block->fd = fd;

    return area;

}

qemu-options.hx

+0 −2
Original line number Diff line number Diff line
@@ -228,7 +228,6 @@ STEXI 
Allocate guest RAM from a temporarily created file in @var{path}.

ETEXI



#ifdef MAP_POPULATE

DEF("mem-prealloc", 0, QEMU_OPTION_mem_prealloc,

    "-mem-prealloc   preallocate guest memory (use with -mem-path)\n",

    QEMU_ARCH_ALL)
@@ -237,7 +236,6 @@ STEXI 
@findex -mem-prealloc

Preallocate memory when using -mem-path.

ETEXI

#endif



DEF("k", HAS_ARG, QEMU_OPTION_k,

    "-k language     use keyboard layout (for example 'fr' for French)\n",

vl.c

+0 −4
Original line number Diff line number Diff line
@@ -188,9 +188,7 @@ static int display_remote; 
const char* keyboard_layout = NULL;

ram_addr_t ram_size;

const char *mem_path = NULL;

#ifdef MAP_POPULATE

int mem_prealloc = 0; /* force preallocation of physical target memory */

#endif

int nb_nics;

NICInfo nd_table[MAX_NICS];

int autostart;
@@ -3206,11 +3204,9 @@ int main(int argc, char **argv, char **envp) 
            case QEMU_OPTION_mempath:

                mem_path = optarg;

                break;

#ifdef MAP_POPULATE

            case QEMU_OPTION_mem_prealloc:

                mem_prealloc = 1;

                break;

#endif

            case QEMU_OPTION_d:

                log_mask = optarg;

                break;