| Message ID | 20191013113940.2863-1-mst@redhat.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | vhost: ring format independence | expand |
On 2019/10/13 下午7:41, Michael S. Tsirkin wrote: > This adds infrastructure required for supporting > multiple ring formats. > > The idea is as follows: we convert descriptors to an > independent format first, and process that converting to > iov later. > > The point is that we have a tight loop that fetches > descriptors, which is good for cache utilization. > This will also allow all kind of batching tricks - > e.g. it seems possible to keep SMAP disabled while > we are fetching multiple descriptors. > > This seems to perform exactly the same as the original > code already based on a microbenchmark. > Lightly tested. > More testing would be very much appreciated. > > To use new code: > echo 1 > /sys/module/vhost_test/parameters/newcode > or > echo 1 > /sys/module/vhost_net/parameters/newcode > > changes from v3: > - fixed error handling in case of indirect descriptors > - add BUG_ON to detect buffer overflow in case of bugs > in response to comment by Jason Wang > - minor code tweaks > > Changes from v2: > - fixed indirect descriptor batching > reported by Jason Wang > > Changes from v1: > - typo fixes I've just done some quick benchmark with testpmd + vhost_net txonly. With 256 queue size, no difference but in 1024 queue size 1% regression of PPS were found. Thanks > > > Michael S. Tsirkin (5): > vhost: option to fetch descriptors through an independent struct > vhost/test: add an option to test new code > vhost: batching fetches > vhost/net: add an option to test new code > vhost: last descriptor must have NEXT clear > > drivers/vhost/net.c | 32 ++++- > drivers/vhost/test.c | 19 ++- > drivers/vhost/vhost.c | 328 +++++++++++++++++++++++++++++++++++++++++- > drivers/vhost/vhost.h | 20 ++- > 4 files changed, 385 insertions(+), 14 deletions(-) >
This adds infrastructure required for supporting multiple ring formats. The idea is as follows: we convert descriptors to an independent format first, and process that converting to iov later. The point is that we have a tight loop that fetches descriptors, which is good for cache utilization. This will also allow all kind of batching tricks - e.g. it seems possible to keep SMAP disabled while we are fetching multiple descriptors. This seems to perform exactly the same as the original code already based on a microbenchmark. Lightly tested. More testing would be very much appreciated. To use new code: echo 1 > /sys/module/vhost_test/parameters/newcode or echo 1 > /sys/module/vhost_net/parameters/newcode changes from v3: - fixed error handling in case of indirect descriptors - add BUG_ON to detect buffer overflow in case of bugs in response to comment by Jason Wang - minor code tweaks Changes from v2: - fixed indirect descriptor batching reported by Jason Wang Changes from v1: - typo fixes Michael S. Tsirkin (5): vhost: option to fetch descriptors through an independent struct vhost/test: add an option to test new code vhost: batching fetches vhost/net: add an option to test new code vhost: last descriptor must have NEXT clear drivers/vhost/net.c | 32 ++++- drivers/vhost/test.c | 19 ++- drivers/vhost/vhost.c | 328 +++++++++++++++++++++++++++++++++++++++++- drivers/vhost/vhost.h | 20 ++- 4 files changed, 385 insertions(+), 14 deletions(-)