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...the memory copy is even slower. The reading performance is over 7 MB/s, with mmap and sendfile enabled, while writing is only 4-5 MB/s. Without mmap and sendfile, reading from samba is also about 4-5 MB/s. I use Oprofile to profile writing file to samba and found that CPU takes over 30% CPU time on copy_from/to_user, so I think going to user space and back again is the bottleneck. Since there is sendfile, why is'nt there counterpart on write path? Is there some difficalties or what? Is it implementable? Please give me some advice. Best Regards, Mac Lin _________________________________________...

..., 2020 at 03:27:39PM +0800, Jason Wang wrote: >> On 2020/6/2 ??9:06, Michael S. Tsirkin wrote: >>> With this patch applied, new and old code perform identically. >>> >>> Lots of extra optimizations are now possible, e.g. >>> we can fetch multiple heads with copy_from/to_user now. >>> We can get rid of maintaining the log array. Etc etc. >>> >>> Signed-off-by: Michael S. Tsirkin<mst at redhat.com> >>> Signed-off-by: Eugenio P?rez<eperezma at redhat.com> >>> Link:https://lore.kernel.org/r/20200401183118.83...

..., 2020 at 03:27:39PM +0800, Jason Wang wrote: >> On 2020/6/2 ??9:06, Michael S. Tsirkin wrote: >>> With this patch applied, new and old code perform identically. >>> >>> Lots of extra optimizations are now possible, e.g. >>> we can fetch multiple heads with copy_from/to_user now. >>> We can get rid of maintaining the log array. Etc etc. >>> >>> Signed-off-by: Michael S. Tsirkin<mst at redhat.com> >>> Signed-off-by: Eugenio P?rez<eperezma at redhat.com> >>> Link:https://lore.kernel.org/r/20200401183118.83...

On Thu, Feb 06, 2020 at 04:12:21PM +0100, Christian Borntraeger wrote: > > > On 06.02.20 15:22, eperezma at redhat.com wrote: > > Hi Christian. > > > > Could you try this patch on top of ("38ced0208491 vhost: use batched version by default")? > > > > It will not solve your first random crash but it should help with the lost of network

On Thu, Feb 06, 2020 at 04:12:21PM +0100, Christian Borntraeger wrote: > > > On 06.02.20 15:22, eperezma at redhat.com wrote: > > Hi Christian. > > > > Could you try this patch on top of ("38ced0208491 vhost: use batched version by default")? > > > > It will not solve your first random crash but it should help with the lost of network

...0400 > >> > >> vhost: batching fetches > >> > >> With this patch applied, new and old code perform identically. > >> > >> Lots of extra optimizations are now possible, e.g. > >> we can fetch multiple heads with copy_from/to_user now. > >> We can get rid of maintaining the log array. Etc etc. > >> > >> Signed-off-by: Michael S. Tsirkin <mst at redhat.com> > >> > >> drivers/vhost/test.c | 2 +- > >> drivers/vhost/vhost.c | 39 +++++++++++++++...

...1 #define dprintk printk @@ -595,51 +595,6 @@ static struct kioctx *lookup_ioctx(unsigned long ctx_id) } /* - * use_mm - * Makes the calling kernel thread take on the specified - * mm context. - * Called by the retry thread execute retries within the - * iocb issuer's mm context, so that copy_from/to_user - * operations work seamlessly for aio. - * (Note: this routine is intended to be called only - * from a kernel thread context) - */ -static void use_mm(struct mm_struct *mm) -{ - struct mm_struct *active_mm; - struct task_struct *tsk = current; - - task_lock(tsk); - active_mm = tsk->act...

...1 #define dprintk printk @@ -595,51 +595,6 @@ static struct kioctx *lookup_ioctx(unsigned long ctx_id) } /* - * use_mm - * Makes the calling kernel thread take on the specified - * mm context. - * Called by the retry thread execute retries within the - * iocb issuer's mm context, so that copy_from/to_user - * operations work seamlessly for aio. - * (Note: this routine is intended to be called only - * from a kernel thread context) - */ -static void use_mm(struct mm_struct *mm) -{ - struct mm_struct *active_mm; - struct task_struct *tsk = current; - - task_lock(tsk); - active_mm = tsk->act...

...1 #define dprintk printk @@ -595,51 +595,6 @@ static struct kioctx *lookup_ioctx(unsigned long ctx_id) } /* - * use_mm - * Makes the calling kernel thread take on the specified - * mm context. - * Called by the retry thread execute retries within the - * iocb issuer's mm context, so that copy_from/to_user - * operations work seamlessly for aio. - * (Note: this routine is intended to be called only - * from a kernel thread context) - */ -static void use_mm(struct mm_struct *mm) -{ - struct mm_struct *active_mm; - struct task_struct *tsk = current; - - task_lock(tsk); - active_mm = tsk->act...

...1 #define dprintk printk @@ -595,51 +595,6 @@ static struct kioctx *lookup_ioctx(unsigned long ctx_id) } /* - * use_mm - * Makes the calling kernel thread take on the specified - * mm context. - * Called by the retry thread execute retries within the - * iocb issuer's mm context, so that copy_from/to_user - * operations work seamlessly for aio. - * (Note: this routine is intended to be called only - * from a kernel thread context) - */ -static void use_mm(struct mm_struct *mm) -{ - struct mm_struct *active_mm; - struct task_struct *tsk = current; - - task_lock(tsk); - active_mm = tsk->act...

...1 #define dprintk printk @@ -595,51 +595,6 @@ static struct kioctx *lookup_ioctx(unsigned long ctx_id) } /* - * use_mm - * Makes the calling kernel thread take on the specified - * mm context. - * Called by the retry thread execute retries within the - * iocb issuer's mm context, so that copy_from/to_user - * operations work seamlessly for aio. - * (Note: this routine is intended to be called only - * from a kernel thread context) - */ -static void use_mm(struct mm_struct *mm) -{ - struct mm_struct *active_mm; - struct task_struct *tsk = current; - - task_lock(tsk); - active_mm = tsk->act...

...1 #define dprintk printk @@ -595,51 +595,6 @@ static struct kioctx *lookup_ioctx(unsigned long ctx_id) } /* - * use_mm - * Makes the calling kernel thread take on the specified - * mm context. - * Called by the retry thread execute retries within the - * iocb issuer's mm context, so that copy_from/to_user - * operations work seamlessly for aio. - * (Note: this routine is intended to be called only - * from a kernel thread context) - */ -static void use_mm(struct mm_struct *mm) -{ - struct mm_struct *active_mm; - struct task_struct *tsk = current; - - task_lock(tsk); - active_mm = tsk->act...

...1 #define dprintk printk @@ -595,51 +595,6 @@ static struct kioctx *lookup_ioctx(unsigned long ctx_id) } /* - * use_mm - * Makes the calling kernel thread take on the specified - * mm context. - * Called by the retry thread execute retries within the - * iocb issuer's mm context, so that copy_from/to_user - * operations work seamlessly for aio. - * (Note: this routine is intended to be called only - * from a kernel thread context) - */ -static void use_mm(struct mm_struct *mm) -{ - struct mm_struct *active_mm; - struct task_struct *tsk = current; - - task_lock(tsk); - active_mm = tsk->act...

...1 #define dprintk printk @@ -595,51 +595,6 @@ static struct kioctx *lookup_ioctx(unsigned long ctx_id) } /* - * use_mm - * Makes the calling kernel thread take on the specified - * mm context. - * Called by the retry thread execute retries within the - * iocb issuer's mm context, so that copy_from/to_user - * operations work seamlessly for aio. - * (Note: this routine is intended to be called only - * from a kernel thread context) - */ -static void use_mm(struct mm_struct *mm) -{ - struct mm_struct *active_mm; - struct task_struct *tsk = current; - - task_lock(tsk); - active_mm = tsk->act...

...1 #define dprintk printk @@ -595,51 +595,6 @@ static struct kioctx *lookup_ioctx(unsigned long ctx_id) } /* - * use_mm - * Makes the calling kernel thread take on the specified - * mm context. - * Called by the retry thread execute retries within the - * iocb issuer's mm context, so that copy_from/to_user - * operations work seamlessly for aio. - * (Note: this routine is intended to be called only - * from a kernel thread context) - */ -static void use_mm(struct mm_struct *mm) -{ - struct mm_struct *active_mm; - struct task_struct *tsk = current; - - task_lock(tsk); - active_mm = tsk->act...

...1 #define dprintk printk @@ -595,51 +595,6 @@ static struct kioctx *lookup_ioctx(unsigned long ctx_id) } /* - * use_mm - * Makes the calling kernel thread take on the specified - * mm context. - * Called by the retry thread execute retries within the - * iocb issuer's mm context, so that copy_from/to_user - * operations work seamlessly for aio. - * (Note: this routine is intended to be called only - * from a kernel thread context) - */ -static void use_mm(struct mm_struct *mm) -{ - struct mm_struct *active_mm; - struct task_struct *tsk = current; - - task_lock(tsk); - active_mm = tsk->act...

...rote: >>>> On 2020/6/2 ??9:06, Michael S. Tsirkin wrote: >>>>> With this patch applied, new and old code perform identically. >>>>> >>>>> Lots of extra optimizations are now possible, e.g. >>>>> we can fetch multiple heads with copy_from/to_user now. >>>>> We can get rid of maintaining the log array. Etc etc. >>>>> >>>>> Signed-off-by: Michael S. Tsirkin<mst at redhat.com> >>>>> Signed-off-by: Eugenio P?rez<eperezma at redhat.com> >>>>> Link:htt...

On 2020/6/2 ??9:06, Michael S. Tsirkin wrote: > With this patch applied, new and old code perform identically. > > Lots of extra optimizations are now possible, e.g. > we can fetch multiple heads with copy_from/to_user now. > We can get rid of maintaining the log array. Etc etc. > > Signed-off-by: Michael S. Tsirkin <mst at redhat.com> > Signed-off-by: Eugenio P?rez <eperezma at redhat.com> > Link: https://lore.kernel.org/r/20200401183118.8334-4-eperezma at redhat.com > Sign...

On 2020/6/2 ??9:06, Michael S. Tsirkin wrote: > With this patch applied, new and old code perform identically. > > Lots of extra optimizations are now possible, e.g. > we can fetch multiple heads with copy_from/to_user now. > We can get rid of maintaining the log array. Etc etc. > > Signed-off-by: Michael S. Tsirkin <mst at redhat.com> > Signed-off-by: Eugenio P?rez <eperezma at redhat.com> > Link: https://lore.kernel.org/r/20200401183118.8334-4-eperezma at redhat.com > Sign...

On 2019/10/11 ??9:46, Michael S. Tsirkin wrote: > With this patch applied, new and old code perform identically. > > Lots of extra optimizations are now possible, e.g. > we can fetch multiple heads with copy_from/to_user now. > We can get rid of maintaining the log array. Etc etc. > > Signed-off-by: Michael S. Tsirkin <mst at redhat.com> > --- > drivers/vhost/test.c | 2 +- > drivers/vhost/vhost.c | 50 ++++++++++++++++++++++++++++++++++++------- > drivers/vhost/vhost.h |...