On 2020/7/17 上午1:16, Eugenio Perez Martin wrote:
On Fri, Jul 10, 2020 at 7:58 AM Michael S. Tsirkin <mst@xxxxxxxxxx> wrote:
On Fri, Jul 10, 2020 at 07:39:26AM +0200, Eugenio Perez Martin wrote:
How about playing with the batch size? Make it a mod parameter instead
of the hard coded 64, and measure for all values 1 to 64 ...
Right, according to the test result, 64 seems to be too aggressive in
the case of TX.
Got it, thanks both!
In particular I wonder whether with batch size 1
we get same performance as without batching
(would indicate 64 is too aggressive)
or not (would indicate one of the code changes
affects performance in an unexpected way).
--
MST
Hi!
Varying batch_size as drivers/vhost/net.c:VHOST_NET_BATCH,
Did you mean varying the value of VHOST_NET_BATCH itself or the number
of batched descriptors?
and testing
the pps as previous mail says. This means that we have either only
vhost_net batching (in base testing, like previously to apply this
patch) or both batching sizes the same.
I've checked that vhost process (and pktgen) goes 100% cpu also.
For tx: Batching decrements always the performance, in all cases. Not
sure why bufapi made things better the last time.
Batching makes improvements until 64 bufs, I see increments of pps but like 1%.
For rx: Batching always improves performance. It seems that if we
batch little, bufapi decreases performance, but beyond 64, bufapi is
much better. The bufapi version keeps improving until I set a batching
of 1024. So I guess it is super good to have a bunch of buffers to
receive.
Since with this test I cannot disable event_idx or things like that,
what would be the next step for testing?
Thanks!
--
Results:
# Buf size: 1,16,32,64,128,256,512
# Tx
# ===
# Base
2293304.308,3396057.769,3540860.615,3636056.077,3332950.846,3694276.154,3689820
What's the meaning of buf size in the context of "base"?
And I wonder maybe perf diff can help.
Thanks
# Batch
2286723.857,3307191.643,3400346.571,3452527.786,3460766.857,3431042.5,3440722.286
# Batch + Bufapi
2257970.769,3151268.385,3260150.538,3379383.846,3424028.846,3433384.308,3385635.231,3406554.538
# Rx
# ==
# pktgen results (pps)
1223275,1668868,1728794,1769261,1808574,1837252,1846436
1456924,1797901,1831234,1868746,1877508,1931598,1936402
1368923,1719716,1794373,1865170,1884803,1916021,1975160
# Testpmd pps results
1222698.143,1670604,1731040.6,1769218,1811206,1839308.75,1848478.75
1450140.5,1799985.75,1834089.75,1871290,1880005.5,1934147.25,1939034
1370621,1721858,1796287.75,1866618.5,1885466.5,1918670.75,1976173.5,1988760.75,1978316
pktgen was run again for rx with 1024 and 2048 buf size, giving
1988760.75 and 1978316 pps. Testpmd goes the same way.
