[libvirt] [test-API][PATCH V2] managedsave: change the checking method about bypass cache

[Guannan Ren]

On 12/25/2012 12:04 PM, hongming wrote:
> Check whether the O_DIRECT flag is in use on the managed save file
> during the duration of the managed save, since that is the real effect
> of the current implementation of the --bypass-cache flag.
> Add break condition into the while loop of get_fileflags()
> method in the PATCH V2
> ---
>   repos/managedsave/managedsave.py |   61 ++++++++++++++++++++------------------
>   1 files changed, 32 insertions(+), 29 deletions(-)
>
> diff --git a/repos/managedsave/managedsave.py b/repos/managedsave/managedsave.py
> index 4a92151..70d4ebc 100644
> --- a/repos/managedsave/managedsave.py
> +++ b/repos/managedsave/managedsave.py
> @@ -2,6 +2,8 @@
>   
>   import os
>   import math
> +import thread
> +import time
>   
>   import libvirt
>   from libvirt import libvirtError
> @@ -39,39 +41,43 @@ def check_savefile_create(*args):
>           logger.info("managed save file exists")
>           return True
>   
> -def compare_cachedfile(cachebefore, cacheafter):
> -    """Compare cached value before managed save and its value after
> -    managed save """
> +def get_fileflags():
> +    """Get the file flags of managed save file"""
> +    cmds = "cat /proc/$(lsof -w /var/lib/libvirt/qemu/save/"+guestname+".save"\
> +    "|awk '/libvirt_i/{print $2}')/fdinfo/1|grep flags|awk '{print $NF}'"
> +    global fileflags
> +    while True:
> +        (status, output) = utils.exec_cmd(cmds, shell=True)
> +        if status == 0:
> +	    if len(output) == 1:
> +	        logger.info("The flags of saved file %s " % output[0])
> +                fileflags = output[0][-5]
> +		break
> +        else:
> +            logger.error("Fail to get the flags of saved file")
> +            return 1
> +
> +    thread.exit_thread()
>   
> -    diff = cacheafter - cachebefore
> -    logger.info("diff is %s " % diff)
> -    percent = math.fabs(diff)/cachebefore
> -    logger.info("diff percent is %s " % percent)
> -    if percent < 0.05:
> +def check_fileflag(fileflags):
> +    """Check the file flags of managed save file if include O_DIRECT"""
> +    if int(fileflags) == 4:
> +        logger.info("file flags include O_DIRECT")
>           return True
>       else:
> +        logger.error("file flags doesn't include O_DIRECT")
>           return False
>   
> -def get_cachevalue():
> -    """Get the file system cached value """
> -
> -    cmds = "head -n4 /proc/meminfo|grep Cached|awk '{print $2}'"
> -    (status, output) = utils.exec_cmd(cmds, shell=True)
> -    if status != 0:
> -        logger.error("Fail to run cmd line to get cache")
> -        return 1
> -    else:
> -        logger.debug(output[0])
> -    cachevalue= int(output[0])
> -    return cachevalue
> -
>   def managedsave(params):
>       """Managed save a running domain"""
>   
>       global logger
>       logger = params['logger']
> +    global guestname
>       guestname = params['guestname']
>       flags = params ['flags']
> +    global fileflags
> +    fileflags = ''
>       #Save given flags to sharedmod.data
>       sharedmod.data['flagsave'] = flags
>   
> @@ -122,17 +128,14 @@ def managedsave(params):
>   
>           #If given flags include bypass-cache,check if bypass file system cache
>           if flagn % 2 == 1:
> -            logger.info("Given flags include --bypass-cache")
> -            os.system('echo 3 > /proc/sys/vm/drop_caches')
> -            cache_before = get_cachevalue()
> -            logger.info("Cached value before managedsave is %s" % cache_before)
> +            logger.info("Given flags include --bypass-cache")
> +            thread.start_new_thread(get_fileflags,())
>   
> +	    # Guarantee get_fileflags shell has run before managed save
> +            time.sleep(5)
>               domobj.managedSave(flagn)
>   
> -            cache_after = get_cachevalue()
> -            logger.info("Cached value after managedsave is %s" % cache_after)
> -
> -            if compare_cachedfile(cache_before, cache_after):
> +            if check_fileflag(fileflags):
>                   logger.info("Bypass file system cache successfully")
>               else:
>                   logger.error("Bypass file system cache failed")

    ACK and pushed.
    Thanks

    Guannan