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virtio-devices: Optimize add_used() usage

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Now that we rely on pop_descriptor_chain() rather than iter() to iterate
over a queue, there's no more borrow on the queue itself, meaning we can
invoke add_used() directly for the iteration loop. This simplifies the
processing of the queues for each virtio device, and bring some possible
performance improvement given we don't have to iterate twice over the
list of descriptors to invoke add_used().

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This commit is contained in:
Sebastien Boeuf
2022-07-25 14:26:17 +02:00
committed by Rob Bradford
parent 87f57f7c1e
commit a4859ffe85
11 changed files with 111 additions and 179 deletions
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57
virtio-devices/src/balloon.rs
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@@ -22,7 +22,6 @@ use libc::EFD_NONBLOCK;
use seccompiler::SeccompAction;
use std::io;
use std::mem::size_of;
use std::ops::Deref;
use std::os::unix::io::AsRawFd;
use std::result;
use std::sync::{
@@ -31,7 +30,7 @@ use std::sync::{
};
use versionize::{VersionMap, Versionize, VersionizeResult};
use versionize_derive::Versionize;
use virtio_queue::{Queue, QueueOwnedT, QueueT};
use virtio_queue::{Queue, QueueT};
use vm_memory::{
Address, ByteValued, Bytes, GuestAddress, GuestAddressSpace, GuestMemory, GuestMemoryAtomic,
GuestMemoryError, GuestMemoryRegion,
@@ -227,34 +226,13 @@ impl BalloonEpollHandler {
Self::advise_memory_range(memory, range_base, range_len, libc::MADV_DONTNEED)
}
fn notify_queue(
&mut self,
queue_index: usize,
used_descs: Vec<(u16, u32)>,
) -> result::Result<(), Error> {
let mem = self.mem.memory();
for (desc_index, len) in used_descs.iter() {
self.queues[queue_index]
.add_used(mem.deref(), *desc_index, *len)
.map_err(Error::QueueAddUsed)?;
}
if !used_descs.is_empty() {
self.signal(VirtioInterruptType::Queue(queue_index as u16))?;
}
Ok(())
}
fn process_queue(&mut self, queue_index: usize) -> result::Result<(), Error> {
let mut used_descs = Vec::new();
let mut used_descs = false;
while let Some(mut desc_chain) =
self.queues[queue_index].pop_descriptor_chain(self.mem.memory())
{
let desc = desc_chain.next().ok_or(Error::DescriptorChainTooShort)?;
used_descs.push((desc_chain.head_index(), desc.len()));
let data_chunk_size = size_of::<u32>();
// The head contains the request type which MUST be readable.
@@ -294,18 +272,24 @@ impl BalloonEpollHandler {
_ => return Err(Error::InvalidQueueIndex(queue_index)),
}
}
self.queues[queue_index]
.add_used(desc_chain.memory(), desc_chain.head_index(), desc.len())
.map_err(Error::QueueAddUsed)?;
used_descs = true;
}
self.notify_queue(queue_index, used_descs)
if used_descs {
self.signal(VirtioInterruptType::Queue(queue_index as u16))
} else {
Ok(())
}
}
fn process_reporting_queue(&mut self, queue_index: usize) -> result::Result<(), Error> {
let mem = self.mem.memory();
let mut used_descs = Vec::new();
for mut desc_chain in self.queues[queue_index]
.iter(mem)
.map_err(Error::QueueIterator)?
let mut used_descs = false;
while let Some(mut desc_chain) =
self.queues[queue_index].pop_descriptor_chain(self.mem.memory())
{
let mut descs_len = 0;
while let Some(desc) = desc_chain.next() {
@@ -313,10 +297,17 @@ impl BalloonEpollHandler {
Self::release_memory_range(desc_chain.memory(), desc.addr(), desc.len() as usize)?;
}
used_descs.push((desc_chain.head_index(), descs_len));
self.queues[queue_index]
.add_used(desc_chain.memory(), desc_chain.head_index(), descs_len)
.map_err(Error::QueueAddUsed)?;
used_descs = true;
}
self.notify_queue(queue_index, used_descs)
if used_descs {
self.signal(VirtioInterruptType::Queue(queue_index as u16))
} else {
Ok(())
}
}
fn run(