search for: max_pend

On 02/25/2014 09:57 PM, Michael S. Tsirkin wrote: > On Tue, Feb 25, 2014 at 02:53:58PM +0800, Jason Wang wrote: >> We used to stop the handling of tx when the number of pending DMAs >> exceeds VHOST_MAX_PEND. This is used to reduce the memory occupation >> of both host and guest. But it was too aggressive in some cases, since >> any delay or blocking of a single packet may delay or block the guest >> transmission. Consider the following setup: >> >> +-----+ +--...

On 02/25/2014 09:57 PM, Michael S. Tsirkin wrote: > On Tue, Feb 25, 2014 at 02:53:58PM +0800, Jason Wang wrote: >> We used to stop the handling of tx when the number of pending DMAs >> exceeds VHOST_MAX_PEND. This is used to reduce the memory occupation >> of both host and guest. But it was too aggressive in some cases, since >> any delay or blocking of a single packet may delay or block the guest >> transmission. Consider the following setup: >> >> +-----+ +--...

...yu wrote: > On 2014/2/26 13:53, Jason Wang wrote: >> On 02/25/2014 09:57 PM, Michael S. Tsirkin wrote: >>> On Tue, Feb 25, 2014 at 02:53:58PM +0800, Jason Wang wrote: >>>> We used to stop the handling of tx when the number of pending DMAs >>>> exceeds VHOST_MAX_PEND. This is used to reduce the memory occupation >>>> of both host and guest. But it was too aggressive in some cases, since >>>> any delay or blocking of a single packet may delay or block the guest >>>> transmission. Consider the following setup: >>>>...

...yu wrote: > On 2014/2/26 13:53, Jason Wang wrote: >> On 02/25/2014 09:57 PM, Michael S. Tsirkin wrote: >>> On Tue, Feb 25, 2014 at 02:53:58PM +0800, Jason Wang wrote: >>>> We used to stop the handling of tx when the number of pending DMAs >>>> exceeds VHOST_MAX_PEND. This is used to reduce the memory occupation >>>> of both host and guest. But it was too aggressive in some cases, since >>>> any delay or blocking of a single packet may delay or block the guest >>>> transmission. Consider the following setup: >>>>...

...M, Michael S. Tsirkin wrote: >>>>> > >>>On Tue, Feb 25, 2014 at 02:53:58PM +0800, Jason Wang wrote: >>>>>> > >>>>We used to stop the handling of tx when the number of pending DMAs >>>>>> > >>>>exceeds VHOST_MAX_PEND. This is used to reduce the memory occupation >>>>>> > >>>>of both host and guest. But it was too aggressive in some cases, since >>>>>> > >>>>any delay or blocking of a single packet may delay or block the guest >>>>>...

...M, Michael S. Tsirkin wrote: >>>>> > >>>On Tue, Feb 25, 2014 at 02:53:58PM +0800, Jason Wang wrote: >>>>>> > >>>>We used to stop the handling of tx when the number of pending DMAs >>>>>> > >>>>exceeds VHOST_MAX_PEND. This is used to reduce the memory occupation >>>>>> > >>>>of both host and guest. But it was too aggressive in some cases, since >>>>>> > >>>>any delay or blocking of a single packet may delay or block the guest >>>>>...

We used to stop the handling of tx when the number of pending DMAs exceeds VHOST_MAX_PEND. This is used to reduce the memory occupation of both host and guest. But it was too aggressive in some cases, since any delay or blocking of a single packet may delay or block the guest transmission. Consider the following setup: +-----+ +-----+ | VM1 | | VM2 | +--+--+...

We used to stop the handling of tx when the number of pending DMAs exceeds VHOST_MAX_PEND. This is used to reduce the memory occupation of both host and guest. But it was too aggressive in some cases, since any delay or blocking of a single packet may delay or block the guest transmission. Consider the following setup: +-----+ +-----+ | VM1 | | VM2 | +--+--+...

On Tue, Feb 25, 2014 at 02:53:58PM +0800, Jason Wang wrote: > We used to stop the handling of tx when the number of pending DMAs > exceeds VHOST_MAX_PEND. This is used to reduce the memory occupation > of both host and guest. But it was too aggressive in some cases, since > any delay or blocking of a single packet may delay or block the guest > transmission. Consider the following setup: > > +-----+ +-----+ > | VM1...

...n 2014/2/26 13:53, Jason Wang wrote: > >>On 02/25/2014 09:57 PM, Michael S. Tsirkin wrote: > >>>On Tue, Feb 25, 2014 at 02:53:58PM +0800, Jason Wang wrote: > >>>>We used to stop the handling of tx when the number of pending DMAs > >>>>exceeds VHOST_MAX_PEND. This is used to reduce the memory occupation > >>>>of both host and guest. But it was too aggressive in some cases, since > >>>>any delay or blocking of a single packet may delay or block the guest > >>>>transmission. Consider the following setup: >...

On 2014/2/26 13:53, Jason Wang wrote: > On 02/25/2014 09:57 PM, Michael S. Tsirkin wrote: >> On Tue, Feb 25, 2014 at 02:53:58PM +0800, Jason Wang wrote: >>> We used to stop the handling of tx when the number of pending DMAs >>> exceeds VHOST_MAX_PEND. This is used to reduce the memory occupation >>> of both host and guest. But it was too aggressive in some cases, since >>> any delay or blocking of a single packet may delay or block the guest >>> transmission. Consider the following setup: >>> >>>...

I have historically noticed that in ZFS, when ever there is a heavy writer to a pool via NFS, the reads can held back (basically paused). An example is a RAID10 pool of 6 disks, whereby a directory of files including some large 100+MB in size being written can cause other clients over NFS to pause for seconds (5-30 or so). This on B70 bits. I''ve gotten used to this behavior over NFS, but