Messages in this thread | | | Subject | Re: [PATCH RFC v8 02/11] vhost: use batched get_vq_desc version | From | Jason Wang <> | Date | Mon, 20 Jul 2020 16:55:20 +0800 |
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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@redhat.com> 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. >
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